[Python-Dev] ConfigParser with a single section (original) (raw)

Detlef Lannert lannert-pydev@lannert.rz.uni-duesseldorf.de
Fri, 8 Nov 2002 16:50:56 +0100

[Gustavo Niemeyer]

Patch #549037 implements an interesting feature: it allows one to have configuration files without headers. I'd like to know what's your opinion about this issue, so that we can either forget the issue or implement the functionality, closing that bug.

[Tim Peters]

-0. Complicates the code and the docs and the mental model to save what, 3 measly characters of typing (e.g., "[x]")?

It also saves me to explain to the users of my program why they have to start each configuration file with a line containing "[Options]", even if there can't be anything other than options in this file. (Making them type "[x]" instead of "[Options]" is even harder <.5 wink>).

Unfortunately I cannot easily supply the section line when parsing the config file, even if I use ConfigParser.readfp(); the "obvious solution"

prefix = cStringIO.StringIO("[Options]\n")
cfp = ConfigParser.ConfigParser()
cfp.readfp(prefix, filename)
cfp.read(filename)

doesn't work because the ConfigParser object expects a new section header for each read*() call.

A generator that encapsulates the file and supplies an initial section header doesn't work either because the ConfigParser uses the readline() method; it doesn't iterate over the file.

Subclassing the ConfigParser class doesn't help much because the _read() method does most of the relevant work and at the same time requires the section header line. So this would basically mean I had to copy that method (~60 lines) and tweak it to handle the case of missing section headers. [I had tried this before I submitted the patch.]

[Gustavo Niemeyer, in a preceding mail]

The patch includes a new parameter in read functions, stating what's the first section name. It means that we could have other sections after the first unheaded section. IMO, that situation should still be considered an error.

Not necessarily an error; I was thinking of a configuration file like

spam = available
frob = required
# ... more general options

[Holidays]
frob = optional
# ... more options for a special case

# etc.

where labelled, optional sections may follow the (usually unlabelled) main configuration section. If the caller doesn't want this, he can easily detect this situation (checking cfp.sections()) and reject/handle it.

Detlef