Pretty Printers

GDB Pretty Printers for STL display nicely formatted variables in the hover pop-up and watch window, for all STL containers (vectors, maps, etc).

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Test with GDB

• Ensure GDB is python-enabled. For Linux (tested with recent Ubuntu), it is enabled by default. For Windows, MinGW's GDB is not python enabled. One option is to install MinGW-Builds over MinGW (consider backing up MinGW first). This updates GCC to 4.7.2 and includes a Python enabled GDB.

To test, launch GDB from console:

(gdb) python print sys.version

If python is enabled, the version will be printed (probably 2.7.x), otherwise, a message will indicate python scripting is not supported.

• Download printers.py (if necessary)

Windows users with MinGW should already have this file in /MinGW/share/gcc-4.7.2/python/libstdcxx/v6.

Linux users can download printers.py here. Save as /home/username/gdb_printers/printers.py.

• Create a GDB Command File to enable the printer. Store in c:\mingw\bin\pp.gdb (windows) or /home/username/gdb_printers/pp.gdb (linux). Below is a sample command file. Replace the path c:/MinGW/share... with your path to printers.py.

python
import sys
sys.path.insert(0, 'c:/MinGW/share/gcc-4.7.2/python/libstdcxx/v6')
from printers import register_libstdcxx_printers
register_libstdcxx_printers (None)
end

• Test

1. Set a breakpoint in a program and debug
2. Run the command file from GDB (can use Codeblocks->debugger tab->command, or in GDB from the console) (substitute your path if necessary)

(gdb) source c:\MinGW\bin\pp.gdb

3. Test the printer - example:

(gdb) print words2
$1 = std::vector of length 3, capacity 4 = {"one", "two", "three"}

Add to Codeblocks

Once the command file is working correctly, there are two steps to activate in Codeblocks:

1. Set debugger initialization command (substitute your path as necessary):
   Codeblocks->Settings->Debugger->Default->Debugger initialization commands

source c:\MinGW\bin\pp.gdb

NOTE: A bug in the Linux version of Codeblocks may prevent entering anything in the Debugger Initialization Commands field. A work-around is to open a CBP project file via a file manager, which in turn launches Codeblocks and seems to resolve the issue.

2. Disable Codeblocks handling of watch values (needed only for versions older than 17.12):

Codeblocks->Settings->Debugger->Default->Enable Watch Scripts = Unchecked

Other Info

Links:

GDB Python API

GDB Pretty Printing

To Do

The third column in the Codeblocks popup and watch window displays a long unformatted string. Codeblocks is calling the GDB whatis command. Can this command be Pretty-Printed?

See also

• Debugging with Code::Blocks
• Debugger scripts
• Configure GDB pretty printer for Msys2