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`lldb_cruby.py` manages lldb custom commands using functions. The file
is a large list of Python functions, and an init handler to map some of
the Python functions into the debugger, to enable execution of custom
logic during a debugging session.
Since LLDB 3.7 (September 2015) there has also been support for using
python classes rather than bare functions, as long as those classes
implement a specific interface.
This PR Introduces some more defined structure to the LLDB helper
functions by switching from the function based implementation to the
class based one, and providing an auto-loading mechanism by which new
functions can be loaded.
The intention behind this change is to make working with the LLDB
helpers easier, by reducing code duplication, providing a consistent
structure and a clearer API for developers.
The current function based approach has some advantages and
disadvantages
Advantages:
- Adding new code is easy.
- All the code is self contained and searchable.
Disadvantages:
- No visible organisation of the file contents. This means
- Hard to tell which functions are utility functions and which are
available to you in a debugging session
- Lots of code duplication within lldb functions
- Large files quickly become intimidating to work with - for example,
`lldb_disasm.py` was implemented as a seperate Python module because
it was easier to start with a clean slate than add significant amounts
of code to `lldb_cruby.py`
This PR attempts, to fix the disadvantages of the current approach and
maintain, or enhance, the benefits. The new structure of a command looks
like this;
```
class TestCommand(RbBaseCommand):
# program is the keyword the user will type in lldb to execute this command
program = "test"
# help_string will be displayed in lldb when the user uses the help functions
help_string = "This is a test command to show how to implement lldb commands"
# call is where our command logic will be implemented
def call(self, debugger, command, exe_ctx, result):
pass
```
If the command fulfils the following criteria it will then be
auto-loaded when an lldb session is started:
- The package file must exist inside the `commands` directory and the
filename must end in `_command.py`
- The package must implement a class whose name ends in `Command`
- The class inherits from `RbBaseCommand` or at minimum a class that
shares the same interface as `RbBaseCommand` (at minimum this means
defining `__init__` and `__call__`, and using `__call__` to call
`call` which is defined in the subclasses).
- The class must have a class variable `package` that is a String. This
is the name of the command you'll call in the `lldb` debugger.
25 lines
1.2 KiB
Python
25 lines
1.2 KiB
Python
# This is a command template for implementing a helper function inside LLDB. To
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# use this file
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# 1. Copy it and rename the copy so it ends with `_command.py`.
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# 2. Rename the class to something descriptive that ends with Command.
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# 3. Change the program variable to be a descriptive command name
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# 4. Ensure you are inheriting from RbBaseCommand or another command that
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# implements the same interfact
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# This test command inherits from RbBaseCommand which provides access to Ruby
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# globals and utility helpers
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class TestCommand(RbBaseCommand):
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# program is the keyword the user will type in lldb to execute this command
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program = "test"
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# help_string will be displayed in lldb when the user uses the help functions
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help_string = "This is a test command to show how to implement lldb commands"
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# call is where our command logic will be implemented
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def call(self, debugger, command, exe_ctx, result):
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# This method will be called once the LLDB environment has been setup.
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# You will have access to self.target, self.process, self.frame, and
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# self.thread
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#
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# This is where we should implement our command logic
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pass
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