=============== Rope Overview =============== The purpose of this file is to give an overview of some of rope's features. It is incomplete. And some of the features shown here are old and do not show what rope can do in extremes. So if you really want to feel the power of rope try its features and see its unit tests. This file is more suitable for the users. Developers who plan to use rope as a library might find library.txt_ more useful. .. contents:: Table of Contents .. _library.txt: library.html ``.ropeproject`` Folder ======================= Rope uses a folder inside projects for holding project configuration and data. Its default name is ``.ropeproject``, but it can be changed (you can even tell rope not to create this folder). Currently it is used for things such as: * There is a ``config.py`` file in this folder in which you can change project configurations. Have look at the default ``config.py`` file (is created when it does not exist) for more information. * It can be used for saving project history, so that the next time you open the project you can undo past changes. * It can be used for saving object information to help rope object inference. * It can be used for saving global names cache which is used in auto-import. You can change what to save and what not to in the ``config.py`` file. Refactorings ============ This section shows some random refactorings that you can perform using rope. Renaming Attributes ------------------- Consider we have:: class AClass(object): def __init__(self): self.an_attr = 1 def a_method(self, arg): print self.an_attr, arg a_var = AClass() a_var.a_method(a_var.an_attr) After renaming ``an_attr`` to ``new_attr`` and ``a_method`` to ``new_method`` we'll have:: class AClass(object): def __init__(self): self.new_attr = 1 def new_method(self, arg): print self.new_attr, arg a_var = AClass() a_var.new_method(a_var.new_attr) Renaming Function Keyword Parameters ------------------------------------ On:: def a_func(a_param): print a_param a_func(a_param=10) a_func(10) performing rename refactoring on any occurrence of ``a_param`` will result in:: def a_func(new_param): print new_param a_func(new_param=10) a_func(10) Renaming modules ---------------- Consider the project tree is something like:: root/ mod1.py mod2.py ``mod1.py`` contains:: import mod2 from mod2 import AClass mod2.a_func() a_var = AClass() After performing rename refactoring one of the ``mod2`` occurrences in `mod1` we'll get:: import newmod from newmod import AClass newmod.a_func() a_var = AClass() and the new project tree would be:: root/ mod1.py newmod.py Renaming Occurrences In Strings And Comments -------------------------------------------- You can tell rope to rename all occurrences of a name in comments and strings. This can be done by passing ``docs=True`` to `Rename.get_changes()` method. Rope renames names in comments and strings only where the name is visible. For example in:: def f(): a_var = 1 # INFO: I'm printing `a_var` print 'a_var = %s' % a_var # f prints a_var after we rename the `a_var` local variable in `f()` to `new_var` we would get:: def f(): new_var = 1 # INFO: I'm printing `new_var` print 'new_var = %s' % new_var # f prints a_var This makes it safe to assume that this option does not perform wrong renames most of the time. This also changes occurrences inside evaluated strings:: def func(): print 'func() called' eval('func()') After renaming `func` to `newfunc` we should have:: def newfunc(): print 'newfunc() called' eval('newfunc()') Rename When Unsure ------------------ This option tells rope to rename when it doesn't know whether it is an exact match or not. For example after renaming `C.a_func` when the 'rename when unsure' option is set in:: class C(object): def a_func(self): pass def a_func(arg): arg.a_func() C().a_func() we would have:: class C(object): def new_func(self): pass def a_func(arg): arg.new_func() C().new_func() Note that the global `a_func` was not renamed because we are sure that it is not a match. But when using this option there might be some unexpected renames. So only use this option when the name is almost unique and is not defined in other places. Move Method Refactoring ----------------------- It happens when you perform move refactoring on a method of a class. In this refactoring, a method of a class is moved to the class of one of its attributes. The old method will call the new method. If you want to change all of the occurrences of the old method to use the new method you can inline it afterwards. For instance if you perform move method on `a_method` in:: class A(object): pass class B(object): def __init__(self): self.attr = A() def a_method(self): pass b = B() b.a_method() You will be asked for the destination field and the name of the new method. If you use ``attr`` and ``new_method`` in these fields and press enter, you'll have:: class A(object): def new_method(self): pass class B(object): def __init__(self): self.attr = A() def a_method(self): return self.attr.new_method() b = B() b.a_method() Now if you want to change the occurrences of `B.a_method()` to use `A.new_method()`, you can inline `B.a_method()`:: class A(object): def new_method(self): pass class B(object): def __init__(self): self.attr = A() b = B() b.attr.new_method() Moving Fields ------------- Rope does not have a separate refactoring for moving fields. Rope's refactorings are very flexible, though. You can use the rename refactoring to move fields. For instance:: class A(object): pass class B(object): def __init__(self): self.a = A() self.attr = 1 b = B() print(b.attr) consider we want to move `attr` to `A`. We can do that by renaming `attr` to `a.attr`:: class A(object): pass class B(object): def __init__(self): self.a = A() self.a.attr = 1 b = B() print(b.a.attr) You can move the definition of `attr` manually. Extract Method -------------- In these examples ``${region_start}`` and ``${region_end}`` show the selected region for extraction:: def a_func(): a = 1 b = 2 * a c = ${region_start}a * 2 + b * 3${region_end} After performing extract method we'll have:: def a_func(): a = 1 b = 2 * a c = new_func(a, b) def new_func(a, b): return a * 2 + b * 3 For multi-line extractions if we have:: def a_func(): a = 1 ${region_start}b = 2 * a c = a * 2 + b * 3${region_end} print b, c After performing extract method we'll have:: def a_func(): a = 1 b, c = new_func(a) print b, c def new_func(a): b = 2 * a c = a * 2 + b * 3 return b, c Extracting Similar Expressions/Statements ----------------------------------------- When performing extract method or local variable refactorings you can tell rope to extract similar expressions/statements. For instance in:: if True: x = 2 * 3 else: x = 2 * 3 + 1 Extracting ``2 * 3`` will result in:: six = 2 * 3 if True: x = six else: x = six + 1 Extract Method In staticmethods/classmethods -------------------------------------------- The extract method refactoring has been enhanced to handle static and class methods better. For instance in:: class A(object): @staticmethod def f(a): b = a * 2 if you extract ``a * 2`` as a method you'll get:: class A(object): @staticmethod def f(a): b = A.twice(a) @staticmethod def twice(a): return a * 2 Inline Method Refactoring ------------------------- Inline method refactoring can add imports when necessary. For instance consider ``mod1.py`` is:: import sys class C(object): pass def do_something(): print sys.version return C() and ``mod2.py`` is:: import mod1 c = mod1.do_something() After inlining `do_something`, ``mod2.py`` would be:: import mod1 import sys print sys.version c = mod1.C() Rope can inline methods, too:: class C(object): var = 1 def f(self, p): result = self.var + pn return result c = C() x = c.f(1) After inlining `C.f()`, we'll have:: class C(object): var = 1 c = C() result = c.var + pn x = result As another example we will inline a `classmethod`:: class C(object): @classmethod def say_hello(cls, name): return 'Saying hello to %s from %s' % (name, cls.__name__) hello = C.say_hello('Rope') Inlining `say_hello` will result in:: class C(object): pass hello = 'Saying hello to %s from %s' % ('Rope', C.__name__) Inlining Parameters ------------------- `rope.refactor.inline.create_inline()` creates an `InlineParameter` object when performed on a parameter. It passes the default value of the parameter wherever its function is called without passing it. For instance in:: def f(p1=1, p2=1): pass f(3) f() f(3, 4) after inlining p2 parameter will have:: def f(p1=1, p2=1): pass f(3, 2) f(p2=2) f(3, 4) Use Function Refactoring ------------------------ It tries to find the places in which a function can be used and changes the code to call it instead. For instance if mod1 is:: def square(p): return p ** 2 my_var = 3 ** 2 and mod2 is:: another_var = 4 ** 2 if we perform "use function" on square function, mod1 will be:: def square(p): return p ** 2 my_var = square(3) and mod2 will be:: import mod1 another_var = mod1.square(4) Automatic Default Insertion In Change Signature ----------------------------------------------- The `rope.refactor.change_signature.ArgumentReorderer` signature changer takes a parameter called ``autodef``. If not `None`, its value is used whenever rope needs to insert a default for a parameter (that happens when an argument without default is moved after another that has a default value). For instance in:: def f(p1, p2=2): pass if we reorder using:: changers = [ArgumentReorderer([1, 0], autodef='1')] will result in:: def f(p2=2, p1=1): pass Sorting Imports --------------- Organize imports sorts imports, too. It does that according to :PEP:`8`:: [__future__ imports] [standard imports] [third-party imports] [project imports] [the rest of module] Handling Long Imports --------------------- ``Handle long imports`` command trys to make long imports look better by transforming ``import pkg1.pkg2.pkg3.pkg4.mod1`` to ``from pkg1.pkg2.pkg3.pkg4 import mod1``. Long imports can be identified either by having lots of dots or being very long. The default configuration considers imported modules with more than 2 dots or with more than 27 characters to be long. Stoppable Refactorings ---------------------- Some refactorings might take a long time to finish (based on the size of your project). The `get_changes()` method of these refactorings take a parameter called `task_handle`. If you want to monitor or stop these refactoring you can pass a `rope.refactor. taskhandle.TaskHandle` to this method. See `rope.refactor.taskhandle` module for more information. Basic Implicit Interfaces ------------------------- Implicit interfaces are the interfaces that you don't explicitly define; But you expect a group of classes to have some common attributes. These interfaces are very common in dynamic languages; Since we only have implementation inheritance and not interface inheritance. For instance:: class A(object): def count(self): pass class B(object): def count(self): pass def count_for(arg): return arg.count() count_for(A()) count_for(B()) Here we know that there is an implicit interface defined by the function `count_for` that provides `count()`. Here when we rename `A.count()` we expect `B.count()` to be renamed, too. Currently rope supports a basic form of implicit interfaces. When you try to rename an attribute of a parameter, rope renames that attribute for all objects that have been passed to that function in different call sites. That is renaming the occurrence of `count` in `count_for` function to `newcount` will result in:: class A(object): def newcount(self): pass class B(object): def newcount(self): pass def count_for(arg): return arg.newcount() count_for(A()) count_for(B()) This also works for change method signature. Note that this feature relies on rope's object analysis mechanisms to find out the parameters that are passed to a function. Restructurings -------------- `rope.refactor.restructure` can be used for performing restructurings. A restructuring is a program transformation; not as well defined as other refactorings like rename. In this section, we'll see some examples. After this example you might like to have a look at: * `rope.refactor.restructure` for more examples and features not described here like adding imports to changed modules. * `rope.refactor.wildcards` for an overview of the arguments the default wildcard supports. Finally, restructurings can be improved in many ways (for instance adding new wildcards). You might like to discuss your ideas in the mailing list. Example 1 ''''''''' In its basic form we have a pattern and a goal. Consider we were not aware of the ``**`` operator and wrote our own :: def pow(x, y): result = 1 for i in range(y): result *= x return result print pow(2, 3) Now that we know ``**`` exists we want to use it wherever `pow` is used (there might be hundreds of them!). We can use a pattern like:: pattern: pow(${param1}, ${param2}) Goal can be something like:: goal: ${param1} ** ${param2} Note that ``${...}`` can be used to match expressions. By default every expression at that point will match. You can use the matched names in goal and they will be replaced with the string that was matched in each occurrence. So the outcome of our restructuring will be:: def pow(x, y): result = 1 for i in range(y): result *= x return result print 2 ** 3 It seems to be working but what if `pow` is imported in some module or we have some other function defined in some other module that uses the same name and we don't want to change it. Wildcard arguments come to rescue. Wildcard arguments is a mapping; Its keys are wildcard names that appear in the pattern (the names inside ``${...}``). The values are the parameters that are passed to wildcard matchers. The arguments a wildcard takes is based on its type. For checking the type of a wildcard, we can pass ``type=value`` as an argument; ``value`` should be resolved to a python variable (or reference). For instance for specifying `pow` in this example we can use `mod.pow`. As you see, this string should start from module name. For referencing python builtin types and functions you can use `__builtin__` module (for instance `__builtin__.int`). For solving the mentioned problem, we change our `pattern`. But `goal` remains the same:: pattern: ${pow_func}(${param1}, ${param2}) goal: ${param1} ** ${param2} Consider the name of the module containing our `pow` function is `mod`. ``args`` can be:: pow_func: name=mod.pow If we need to pass more arguments to a wildcard matcher we can use ``,`` to separate them. Such as ``name: type=mod.MyClass,exact``. This restructuring handles aliases; like in:: mypow = pow result = mypow(2, 3) Transforms into:: mypow = pow result = 2 ** 3 If we want to ignore aliases we can pass ``exact`` as another wildcard argument:: pattern: ${pow}(${param1}, ${param2}) goal: ${param1} ** ${param2} args: pow: name=mod.pow, exact ``${name}``, by default, matches every expression at that point; if ``exact`` argument is passed to a wildcard only the specified name will match (for instance, if ``exact`` is specified , ``${name}`` matches ``name`` and ``x.name`` but not ``var`` nor ``(1 + 2)`` while a normal ``${name}`` can match all of them). For performing this refactoring using rope library see `library.txt`_. Example 2 ''''''''' As another example consider:: class A(object): def f(self, p1, p2): print p1 print p2 a = A() a.f(1, 2) Later we decide that `A.f()` is doing too much and we want to divide it to `A.f1()` and `A.f2()`:: class A(object): def f(self, p1, p2): print p1 print p2 def f1(self, p): print p def f2(self, p): print p a = A() a.f(1, 2) But who's going to fix all those nasty occurrences (actually this situation can be handled using inline method refactoring but this is just an example; consider inline refactoring is not implemented yet!). Restructurings come to rescue:: pattern: ${inst}.f(${p1}, ${p2}) goal: ${inst}.f1(${p1}) ${inst}.f2(${p2}) args: inst: type=mod.A After performing we will have:: class A(object): def f(self, p1, p2): print p1 print p2 def f1(self, p): print p def f2(self, p): print p a = A() a.f1(1) a.f2(2) Example 3 ''''''''' If you like to replace every occurrences of ``x.set(y)`` with ``x = y`` when x is an instance of `mod.A` in:: from mod import A a = A() b = A() a.set(b) We can perform a restructuring with these information:: pattern: ${x}.set(${y}) goal: ${x} = ${y} args: x: type=mod.A After performing the above restructuring we'll have:: from mod import A a = A() b = A() a = b Note that ``mod.py`` contains something like:: class A(object): def set(self, arg): pass Issues '''''' Pattern names can appear only at the start of an expression. For instance ``var.${name}`` is invalid. These situations can usually be fixed by specifying good checks, for example on the type of `var` and using a ``${var}.name``. Object Inference ================ This section is a bit out of date. Static object inference can do more than described here (see unittests). Hope to update this someday! Static Object Inference ----------------------- :: class AClass(object): def __init__(self): self.an_attr = 1 def call_a_func(self): return a_func() def a_func(): return AClass() a_var = a_func() #a_var.${codeassist} another_var = a_var #another_var.${codeassist} #another_var.call_a_func().${codeassist} Basic support for builtin types:: a_list = [AClass(), AClass()] for x in a_list: pass #x.${codeassist} #a_list.pop().${codeassist} a_dict = ['text': AClass()] for key, value in a_dict.items(): pass #key.${codeassist} #value.${codeassist} Enhanced static returned object inference:: class C(object): def c_func(self): return [''] def a_func(arg): return arg.c_func() a_var = a_func(C()) Here rope knows that the type of a_var is a `list` that holds `str`\s. Supporting generator functions:: class C(object): pass def a_generator(): yield C() for c in a_generator(): a_var = c Here the objects `a_var` and `c` hold are known. Rope collects different types of data during SOA, like per name data for builtin container types:: l1 = [C()] var1 = l1.pop() l2 = [] l2.append(C()) var2 = l2.pop() Here rope can easily infer the type of `var1`. But for knowing the type of `var2`, it needs to analyze the items inserted into `l2` which might happen in other modules. Rope can do that by running SOA on that module. You might be wondering is there any reason for using DOA instead of SOA. The answer is that DOA might be more accurate and handles complex and dynamic situations. For example in:: def f(arg): return eval(arg) a_var = f('C') SOA can no way conclude the object `a_var` holds but it is really trivial for DOA. What's more SOA only analyzes calls in one module while DOA analyzes any call that happens when running a module. That is, for achieving the same result as DOA you might need to run SOA on more than one module and more than once (not considering dynamic situations.) One advantage of SOA is that it is much faster than DOA. Dynamic Object Analysis ----------------------- `PyCore.run_module()` runs a module and collects object information if ``perform_doa`` project config is set. Since as the program runs rope gathers type information, the program runs much slower. After the program is run, you can get better code assists and some of the refactorings perform much better. ``mod1.py``:: def f1(param): pass #param.${codeassist} #f2(param).${codeassist} def f2(param): #param.${codeassist} return param Using code assist in specified places does not give any information and there is actually no information about the return type of `f2` or `param` parameter of `f1`. ``mod2.py``:: import mod1 class A(object): def a_method(self): pass a_var = A() mod1.f1(a_var) Retry those code assists after performing DOA on `mod2` module. Builtin Container Types ''''''''''''''''''''''' Builtin types can be handled in a limited way, too:: class A(object): def a_method(self): pass def f1(): result = [] result.append(A()) return result returned = f() #returned[0].${codeassist} Test the the proposed completions after running this module. Guessing Function Returned Value Based On Parameters ---------------------------------------------------- ``mod1.py``:: class C1(object): def c1_func(self): pass class C2(object): def c2_func(self): pass def func(arg): if isinstance(arg, C1): return C2() else: return C1() func(C1()) func(C2()) After running `mod1` either SOA or DOA on this module you can test: ``mod2.py``:: import mod1 arg = mod1.C1() a_var = mod1.func(arg) a_var.${codeassist} mod1.func(mod1.C2()).${codeassist} Automatic SOA ------------- When turned on, it analyzes the changed scopes of a file when saving for obtaining object information; So this might make saving files a bit more time consuming. By default, this feature is turned on, but you can turn it off by editing your project ``config.py`` file, though that is not recommended. Validating Object DB -------------------- Since files on disk change over time project objectdb might hold invalid information. Currently there is a basic incremental objectdb validation that can be used to remove or fix out of date information. Rope uses this feature by default but you can disable it by editing ``config.py``. Custom Source Folders ===================== By default rope searches the project for finding source folders (folders that should be searched for finding modules). You can add paths to that list using ``source_folders`` project config. Note that rope guesses project source folders correctly most of the time. You can also extend python path using ``python_path`` config. Version Control Systems Support =============================== When performing refactorings some files might need to be moved (when renaming a module) or new files might be created. When using a VCS, rope detects and uses it to perform file system actions. Currently Mercurial_, GIT_, Darcs_ and SVN (using pysvn_ library) are supported. They are selected based on dot files in project root directory. For instance, Mercurial will be used if `mercurial` module is available and there is a ``.hg`` folder in project root. Rope assumes either all files are under version control in a project or there is no version control at all. Also don't forget to commit your changes yourself, rope doesn't do that. Adding support for other VCSs is easy; have a look at `library.txt`_. .. _pysvn: http://pysvn.tigris.org .. _Mercurial: http://selenic.com/mercurial .. _GIT: http://git.or.cz .. _darcs: http://darcs.net