Problem

It currently seems impossible to escape the # character inside matplotlibrc files. I would like to include it as part of the parameter value for text.latex.preamble to add a LaTeX command definition such as \newcommand{\foo}[1]{\bar{#1}}.

When reading the file, each line is split at the # character and everything after it assumed as comment and thus discarded.

Proposed Solution

One solution would be to replace the line

strippedline = line.split('#', 1)[0].strip()

with a function that escapes # character(s). It would look something like this:

def strip_comment_with_escaped_octothorpe(line):
    splitline = line.split('#')
    escaped_line = []
    for i in range(len(splitline)):
        segment = splitline[i]
        if segment[-1] is '\':  # the character was escaped with '\#'
            segment = segment[:-1]  # remove the escape character '\'
        escaped_line.append(segment)
    if splitline[-2][-1] is '\':  # the last segment was an actual comment
        escaped_line = escaped_line[:-1]
    return ''.join(escaped_line)  # join back

strippedline = strip_comment_with_escaped_octothorpe(line).strip()

Additional context and prior art

Potential other use cases:

• text.latex.preamble and pgf.preamble: Not just limited to \newcommand's #1
• savefig.directory: File paths might contain #
• keymap: the # key cannot be remapped currently