ocstyle

Objective-C style checker

Installation

pip install ocstyle

Example

If you have a file called test.m like this:

@implementation SomeClass

+(void) someMessage:(NSString*)subdomain {
    NSString *ShouldStartLowerCase;
    // ...
}

@end

and test.h like this:

@interface SomeClass

+ (void)someMessage:(NSString*)subdomain;

@property NSInteger value;

@end

You can check style like this:

$ ocstyle test.*
test.h
ERROR: 0:-97 [0] - ExpectedInterfaceDocInHeader - Interface requires /** documentation */
ERROR: 3:30 [51] - MissingSpace - Expected 1, got 0
ERROR: 5:1 [65] - ExpectedPropertyDocInHeader - Property requires /** documentation */

test.m
ERROR: 3:2 [28] - MissingSpace - Expected 1, got 0
ERROR: 3:9 [35] - ExtraSpace - Did not expect ' ' here
ERROR: 3:30 [56] - MissingSpace - Expected 1, got 0
ERROR: 3:42 [68] - MissingNewline - Should have newline after ;
ERROR: 3:42 [68] - MissingSemicolon - Expected a semicolon
ERROR: 4:35 [104] - BadLocalVariableName - Local variable must start with a lower case letter```

Goal

Make it easy to share and enforce style rules for Objective C. The less human time we spend thinking about whitespace and naming the better! Also enforces the existence of basic documentation.

At Cue we use this as a git pre-commit hook. This way we ensure everyone maintains a consistent coding style with a minimum of effort.

Related

OCLint runs static analysis that helps to detect common logic errors. Use it alongside ocstyle!

Status

This is a pretty early stage project. We fully expect bugs and feature requests!

One notable absence is that right now style rules are not configurable. For example, we use the following style for message implementations:

+(void) someMessage:(NSString*)subdomain;
{
}

Note the inclusion of the ; and the { being on the next line. We like this style because it makes it easy to copy and paste from .h to .m and back, but maybe you have your own preferences. We'd be very happy to accept pull requests that make ocstyle more configurable.

For the motivated pull requesters out there, other notable TODOs include:

• Allow inline disabling of specific errors.

• Fix various whitespace false negatives noted in test files

Links

ocstyle is built using parcon, a really nice parser generator library for Python.

Other linters and style checkers we use at Cue include:

• Objective C: OCLint

• Java: checkstyle

• JavaScript: Closure Linter

• Python: pylint and pep8

• All: IntelliJ has great code inspections in the editor

License

Apache License version 2.0

Authors

Cue