1BTOOL_FAQ(1) btparse BTOOL_FAQ(1)
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6 btool_faq - Frequently-Asked Questions about btparse and Text::BibTeX
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9 This document attempts to address questions that I have been asked
10 several times, and are easy to answer -- but not by perusing the
11 documentation. For various reasons, the answers tend to be thinly
12 distributed across several man pages, making it difficult to figure out
13 what's going on. Hence, this man page will attempt to tie together
14 various strands of thought, providing quick, focused, "How do I do X?"
15 answers as opposed to lengthy descriptions of the capabilities and
16 conventions of the btOOL libraries.
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19 This section covers questions that users of "Text::BibTeX", the Perl
20 component of btOOL, have asked.
21 Why aren't the BibTeX "month" macros defined?
23 Because they're bibliography-specific, and "Text::BibTeX" by default
24 doesn't impose any assumptions about a particular type of database or
25 data-processing domain on your entries. The problem arises when you
26 parse entries from a file, say foo.bib that quite sensibly use the
27 month macros ("jan", "feb", etc.) provided by the BibTeX standard style
28 files:
29 $bibfile = Text::BibTeX::File->new('foo.bib') # open file
31 or die "foo.bib: $!\n";
32 $entry = Text::BibTeX::Entry->new($bibfile); # parse first entry
33 Using this code, you might get an "undefined macro" warning for every
35 entry parsed from foo.bib. Apart from the superficial annoyance of all
36 those warning messages, the undefined macros are expanded as empty
37 strings, meaning you lose any information about them---not good.
38 You could always kludge it and forcibly define the month macros
40 yourself. Prior to release 0.30, this had to be done by parsing a set
41 of fake entries, but now "Text::BibTeX" provides a direct interface to
42 the underlying macro table. You could just do this before parsing any
43 entries:
44 use Text::BibTeX qw(:macrosubs);
46 # ...
47 my %month = (jan => 'January', feb => 'February', ... );
48 add_macro_text ($macro, $value)
49 while (($macro, $value) = each %month);
50 But there's a better way that's more in keeping with how things are
52 done under BibTeX (where default macros are defined in the style file):
53 use "Text::BibTeX"'s object-oriented analogue to style files, called
54 structure modules. "Text::BibTeX" provides a structure module,
55 "Text::BibTeX::Bib", that (partially) emulates the standard style files
56 of BibTeX 0.99, including the definition of month macros. Structure
57 modules are specified on a per-file basis by using the "set_structure"
58 method on a "Text::BibTeX::File" object. It's quite simple to tell
59 "Text::BibTeX" that entries from $bibfile are expected to conform to
60 the "Bib" structure (which is implemented by the "Text::BibTeX::Bib"
61 module, but you don't really need to know that):
62 $bibfile = Text::BibTeX::File->new('foo.bib')
64 or die "foo.bib: $!\n";
65 $bibfile->set_structure ('Bib');
66 You probably shouldn't hardcode the name of a particular structure in
68 your programs, though, as there will eventually be a multitude of
69 structure modules to choose from (just as there are a multitude of
70 BibTeX style files to choose from). My preferred approach is to make
71 the structure a command-line option which defaults to "Bib" (since
72 that's the only structure actually implemented as of this writing).
73 How do I append to a BibTeX file?
75 Just open it in append mode, and write entries to it as usual.
76 Remember, a "Text::BibTeX::File" object is mainly a wrapper around an
77 "IO::File" object, and the "Text::BibTeX::File::open" method (and thus
78 "new" as well) is just a front-end to "IO::File::open".
79 "IO::File::open", in turn, is a front-end either to Perl's builtin
80 "open" (if called with one argument) or "sysopen" (two or three
81 arguments). To save you the trouble of going off and reading all those
82 man pages, here's the trick: if you pass just a filename to
83 "Text::BibTeX::File"'s "new" method, then it's treated just like a
84 filename passed to Perl's builtin "open":
85 my $append_file = Text::BibTeX::File->new(">>$filename")
87 or die "couldn't open $filename for appending: $!\n";
88 opens $filename for appending. If, later on, you have an entry from
90 another file (say $entry), then you can append it to $append_file by
91 just writing it as usual:
92 $entry->write ($append_file);
94 See "append_entries" in the examples/ subdirectory of the
96 "Text::BibTeX" distribution for a complete example.
97
99 This section covers frequently-asked questions about btparse, the C
100 component of btOOL.
101 Is there a Python binding for btparse yet?
103 Not that I know of. I haven't written one. If you do so, please let
104 me know about it.
105
107 btparse, Text::BibTeX
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110 Greg Ward <gward@python.net>
111
113 Copyright (c) 1997-2000 by Gregory P. Ward. All rights reserved. This
114 file is part of the Text::BibTeX library. This library is free
115 software; you may redistribute it and/or modify it under the same terms
116 as Perl itself.
117btparse, version 0.88 2021-01-27 BTOOL_FAQ(1)