Difference between revisions of "Logos"

From iPhone Development Wiki
Jump to: navigation, search
m (%hook)
m (List of Logos Directives: Syntax highlight ALL the things!)
Line 22: Line 22:
 
===== %init =====
 
===== %init =====
  
%init
+
<source lang="logos">
%init([<class>=<expr>, …])
+
%init
%init(Group[, [+|-]<class>=<expr>, …])
+
%init([<class>=<expr>, …])
 +
%init(Group[, [+|-]<class>=<expr>, …])
 +
</source>
  
 
Initialize a group (or the default group). Passing no group name will initialize "_ungrouped", and passing class=expr arguments will substitute the given expressions for those classes at initialization time. The + sigil (as in class methods in Objective-C) can be prepended to the classname to substitute an expression for the metaclass. If not specified, the sigil defaults to -, to substitute the class itself. If not specified, the metaclass is derived from the class.
 
Initialize a group (or the default group). Passing no group name will initialize "_ungrouped", and passing class=expr arguments will substitute the given expressions for those classes at initialization time. The + sigil (as in class methods in Objective-C) can be prepended to the classname to substitute an expression for the metaclass. If not specified, the sigil defaults to -, to substitute the class itself. If not specified, the metaclass is derived from the class.
Line 34: Line 36:
 
===== %config =====
 
===== %config =====
  
%config(X=Y)
+
<source lang="logos">%config(X=Y)</source>
  
 
Set a logos configuration flag - currently unused, but the only existing configurable flag is 'generator', and the only generator that exists is "MobileSubstrate"
 
Set a logos configuration flag - currently unused, but the only existing configurable flag is 'generator', and the only generator that exists is "MobileSubstrate"
Line 58: Line 60:
 
===== %subclass =====
 
===== %subclass =====
  
%subclass Classname: Superclass <Protocol, Protocol>
+
<source lang="logos">%subclass Classname: Superclass <Protocol, Protocol></source>
  
 
Subclass block - the class is created at runtime and populated with methods. ivars are not yet supported.
 
Subclass block - the class is created at runtime and populated with methods. ivars are not yet supported.
Line 64: Line 66:
 
===== %group =====
 
===== %group =====
  
%group Groupname
+
<source lang="logos">%group Groupname</source>
  
 
Begin a hook group (for conditional initialization or code organization) with the name ''Groupname''. All ungrouped hooks are in the implicit "_ungrouped" group.
 
Begin a hook group (for conditional initialization or code organization) with the name ''Groupname''. All ungrouped hooks are in the implicit "_ungrouped" group.
Line 70: Line 72:
 
===== %class =====
 
===== %class =====
  
%class Class
+
<source lang="logos">%class Class</source>
  
 
Forward-declare a class. Outmoded by %c, but still exists. Creates a $Class variable, and initializes it with the "_ungrouped" group.
 
Forward-declare a class. Outmoded by %c, but still exists. Creates a $Class variable, and initializes it with the "_ungrouped" group.
Line 76: Line 78:
 
===== %new =====
 
===== %new =====
  
%new(signature)
+
<source lang="logos">%new(signature)</source>
  
 
Add a new method to a hooked class or subclass.
 
Add a new method to a hooked class or subclass.
Line 82: Line 84:
 
===== %ctor =====
 
===== %ctor =====
  
%ctor { … }
+
<source lang="logos">%ctor { … }</source>
  
 
Generate an anonymous constructor (of default priority).
 
Generate an anonymous constructor (of default priority).
Line 88: Line 90:
 
===== %end =====
 
===== %end =====
  
%end
+
<source lang="logos">%end</source>
  
 
Close a hook/subclass/group block.
 
Close a hook/subclass/group block.
Line 96: Line 98:
 
===== %c =====
 
===== %c =====
  
%c(Class)
+
<source lang="logos">%c(Class)</source>
  
 
Effectively evaluates to Class, at runtime. Technically, creates $Class and populates it when the "_ungrouped" group is initialized.
 
Effectively evaluates to Class, at runtime. Technically, creates $Class and populates it when the "_ungrouped" group is initialized.
Line 102: Line 104:
 
===== %orig =====
 
===== %orig =====
  
%orig
+
<source lang="logos">
%orig(args)
+
%orig
 +
%orig(args)
 +
</source>
  
 
Call the original hooked method. Doesn't function in a `%new`'d method. Works in subclasses, strangely enough, because MobileSubstrate will generate a supercall closure at hook time. (If the hooked  
 
Call the original hooked method. Doesn't function in a `%new`'d method. Works in subclasses, strangely enough, because MobileSubstrate will generate a supercall closure at hook time. (If the hooked  
Line 110: Line 114:
 
===== %log =====
 
===== %log =====
  
%log
+
<source lang="logos">%log</source>
  
 
Dump the method arguments to syslog.
 
Dump the method arguments to syslog.
  
 
[[Category:Development Tools]]
 
[[Category:Development Tools]]

Revision as of 08:35, 24 July 2011

Logos is a component of the Theos development suite that allows method hooking code to be written easily and clearly, using a set of special preprocessor directives.

Overview

The syntax provided by Logos greatly simplifies the development of MobileSubstrate extensions ("tweaks") which can hook other methods throughout the OS. In this context, "method hooking" refers to a technique used to replace or modify methods of classes found in other applications on the phone.

Getting Logos

Logos is distributed with Theos, and you can use Logos' syntax in any Theos-built project without any extra setup. For more information about Theos, visit its page.

Using Logos

Examples

Write me!

List of Logos Directives

Initialization

%init
%init
%init([<class>=<expr>, …])
%init(Group[, [+|-]<class>=<expr>, …])

Initialize a group (or the default group). Passing no group name will initialize "_ungrouped", and passing class=expr arguments will substitute the given expressions for those classes at initialization time. The + sigil (as in class methods in Objective-C) can be prepended to the classname to substitute an expression for the metaclass. If not specified, the sigil defaults to -, to substitute the class itself. If not specified, the metaclass is derived from the class.

Block-level

The directives in this category open a block of code which must be closed by an %end directive (shown below).

%config
%config(X=Y)

Set a logos configuration flag - currently unused, but the only existing configurable flag is 'generator', and the only generator that exists is "MobileSubstrate"

%hook
%hook Classname

Open a hook block for the class named Classname.

Here's a trivial example:

%hook SBApplicationController
-(void)uninstallApplication:(SBApplication *)application {
    NSLog(@"Hey, we're hooking uninstallApplication:!");
    %orig;
    return;
}
%end
%subclass
%subclass Classname: Superclass <Protocol, Protocol>

Subclass block - the class is created at runtime and populated with methods. ivars are not yet supported.

%group
%group Groupname

Begin a hook group (for conditional initialization or code organization) with the name Groupname. All ungrouped hooks are in the implicit "_ungrouped" group.

%class
%class Class

Forward-declare a class. Outmoded by %c, but still exists. Creates a $Class variable, and initializes it with the "_ungrouped" group.

%new
%new(signature)

Add a new method to a hooked class or subclass.

%ctor
%ctor {  }

Generate an anonymous constructor (of default priority).

%end
%end

Close a hook/subclass/group block.

Inline

%c
%c(Class)

Effectively evaluates to Class, at runtime. Technically, creates $Class and populates it when the "_ungrouped" group is initialized.

%orig
%orig
%orig(args)

Call the original hooked method. Doesn't function in a `%new`'d method. Works in subclasses, strangely enough, because MobileSubstrate will generate a supercall closure at hook time. (If the hooked method doesn't exist in the class we're hooking, it creates a stub that just calls the superclass implementation.) args is passed to the original function - don't include `self` and `_cmd`, Logos does this for you.

%log
%log

Dump the method arguments to syslog.