On 8/28/20 6:56 AM, Steve Barnes wrote: > > It occurs to me that there are many situations where files are human > authored and can include comments but by default when python > reads/modifies/writes those files by default the comments are lost. > > > > Some examples include configfile, json and even python itself with the > special case that docstrings are read without being discarded. > > > > If we wish to generate a commented file, (such as an initial version > of a config file), then file type specific code is needed but in > general if we read in a file the comments are discarded – usually of > course this is what we need but not if we are going to be modifying > values are re-writing. > > > > In the case of files that are read and parsed into python objects we > could quite easily have an option to make comments a docstring on the > resulting objects and a write option to output the docstrings (marked > as comments). > > > > It would be necessary to have a mechanism for preserving file level > comments that are interleaved with values/objects and after the last > value/object. > > > > Of course, in many cases, it would be nice to have find commented > object and uncomment object, possibly comment out object methods but I > still believe that even without such methods could be useful to be > able to round trip files that include comments. > > > > Writing this has also sparked a thought of wouldn’t it be nice to have > a format for python line comments where the object so commented gets a > docstring from the line comment, e.g. > > > > class StockItem: > > “”” Represents an item available in store “”” > > lineno: str #! Catalogue Item Number in the format AA-nnnn-AAA > > : > > > > The humble docstring can be so useful and as far as I know any python > object can carry one but currently base classes such as int, etc. Have > read only __doc__ members. > > > > Of course I am probably going to get told off for 2 related but > divergent elements in one thread! > > > > Steve Barnes > >
This is just about the first part of your mail: There are external libraries for reading and writing various formats while preserving comments (and even more, e.g. spacing): For Python files, there is RedBaron, for YAML there is ruamel.yaml, and JSON doesn't allow comments as far as I know. For configfile I'm not sure, doesn't look like there is anything... but one could have a look at how comments are represented in RedBaron and ruamel.yaml and write a similar library for configfiles. Cheers
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