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https://github.com/Khan/slicker

a tool for moving things in python
https://github.com/Khan/slicker

Last synced: 23 days ago
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a tool for moving things in python

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README 

        
Slicker: A Tool for Moving Things in Python

-------------------------------------------



[![Build Status](https://travis-ci.org/Khan/slicker.svg?branch=master)](https://travis-ci.org/Khan/slicker)



If you've ever tried to move a function or class in python, you'll find it's

kind of a pain: you have to not only move the definition (and its imports,

etc.) but also update references across the codebase.  Slicker is a tool for

doing just that!



**Note:** At this time Slicker is [Python 2 only](https://github.com/Khan/slicker/issues/21).



## Installation



`pip2 install slicker`



## Usage



To move a function `myfunc` defined in `foo/bar.py` to `foo/baz.py`:

```

slicker foo.bar.myfunc foo.baz.myfunc

```



The same syntax works if `myfunc` is instead a constant or class (although I

sure hope you didn't name a class `myfunc`!).  It also works if you want to

change the name of `myfunc`:

```

slicker foo.bar.myfunc foo.bar.new_name_for_myfunc

```

(And you can also make both changes at once, in the natural way.)



To move an entire module `foo/bar.py` to `foo/baz.py` you can do similarly:

```

slicker foo.bar foo.baz

```

or use filenames like:

```

slicker foo/bar.py foo/baz.py

```



You can also move a symbol into an existing module, or a module into an

existing directory, just like `mv`.  So this is equivalent to the first

example:

```

slicker foo.bar.myfunc foo.baz

```

And to move `foo/bar.py` to a new file `newfoo/bar.py` in an existing directory

`newfoo/`, you could do

```

slicker foo.bar newfoo  # (or slicker foo/bar.py newfoo/)

```

Using this syntax, you can also specify multiple things to move, so you could

move both `foo/bar.py` and `foo/baz.py` to `newfoo/` with

```

slicker foo/bar.py foo/baz.py newfoo/

```



You can tell slicker to use an alias when adding imports using `-a`/`--alias`:

```

slicker foo.bar.myfunc foo.baz.myfunc --alias baz

```

in which case slicker will add `from foo import baz` everywhere instead of

`import foo.baz`.  (You could also have used `--alias foobaz` in which case

we would have done `import foo.baz as foobaz`.)



If you prefer to move the actual definition yourself, and just have slicker

update the references, you can pass `--no-automove`.  It's probably best to run

`slicker` after doing said move.



For a full list of options, run `slicker --help`.



## Frequently and Infrequently Asked Questions



### What does slicker mean if it says "This import may be used implicitly."?



If you do `import foo.bar`, and some other file (perhaps another one you

import) does `import foo.baz`, then your `foo` now also has a `foo.baz`, and so

you can do `foo.baz.func()` with impunity, even though no import in your file

directly mentions that module.  (This is because `foo` in both files refers to

the same object -- a.k.a.  `sys.modules['foo']` -- and so when the other file

does `import foo.baz` it attaches `baz` to that shared object.)  So if you've

asked slicker to move `foo.bar` to `newfoo.bar`, when updating this file, it

would like to replace the `import foo.bar` with `import newfoo.bar`, but it

can't -- you're actually still using the import.  So it will warn you of this

case, and let you sort things out by hand.



### Slicker left me with a bunch of misindented or long lines!



Yep, we don't fix these correctly (yet).  Your linter should tell you what to

fix, though.



### Why is it called slicker?



Because pythons slither to move around, but this way is, uh, slicker.  Which is

to say: it seemed like a good idea at the time and as far as I could tell the

name wasn't already taken.



### How does it work?



See the [blog post](http://engineering.khanacademy.org/posts/slicker.htm) for

an overview.  If that's not enough, bug the authors or read the source!



### Why don't you just use [PyCharm](https://www.jetbrains.com/pycharm/) or [rope](https://github.com/python-rope/rope)?



Good question -- we tried!  Both are great projects and do a lot of things

slicker doesn't; if they work for you then definitely use them.  But for us,

they were a little buggy and didn't fit our workflow.  For more details, see

the [blog post](http://engineering.khanacademy.org/posts/slicker.htm).



### Why don't you just use `codemod` or `sed`/`perl`?



Good question -- we tried!  But it takes a lot of gluing things together to

figure out all the right references to fix up in each file.  And there's

basically no hope of doing the right thing when fixing up string-references.

We needed something that knew what python imports mean and could handle their

special cases.



## Changelog



### 0.9.3



- Fix description on PyPI, again



### 0.9.2



- Fix description on PyPI



### 0.9.1



- Handle relative imports correctly

- Lots of internal refactoring



### 0.9



- Initial release to PyPI