[Octave-bug-tracker] [bug #52479] textscan ignores leading spaces when creating cell from string/file

[Dan Sebald]

Follow-up Comment #4, bug #52479 (project octave):

comment #3: OK, having read the textscan help, the takeaway is that textscan
is a superset of strread() except for possibly different treatment of
whitespace characters?  Hence, it is difficult to make one or the other a main
source routine and re-using it for the other routine?  strread is a script, so
is it slower in some significant way?  It might be better if strread()
utilized textscan() similar to what you described with "whitespace set to
"\t\b"" (instead of going the other way with " \t\b".

Here's the white-space treatment from strread.m:


    ## For numeric fields, whitespace is always a delimiter, but not for text
    ## fields
    if (isempty (regexp (format, '%\*?\d*s')))
      ## Add whitespace to delimiter set
      delimiter_str = unique ([white_spaces delimiter_str]);
    else
      ## Remove any delimiter chars from white_spaces list
      white_spaces = setdiff (white_spaces, delimiter_str);
    endif


Unlike the above, the patch I submitted is always removing the delimiters
regardless of whether the format is %s or numeric.

As an aside, it would be nice if built-in textscan() had tests just like
scripts have tests so that one could tweak some code and immediately get
feedback on what the ramifications are.

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