[Bioperl-l] Failed tests for FeatureIO
torsten.seemann at infotech.monash.edu.au
Mon Sep 25 18:15:13 EDT 2006
> PS: is there any point to using mode() here? As Sendu points out, no
> other Bioperl modules use it. Just curious...
Many file formats that people use Bioperl to parse have this layout:
LINE(S) FOR FEATURE 1
LINE(S) FOR FEATURE 2
Most of the modules (eg. Bio::Tools::*) don't parse HEADER until the
first call of next_feature(), kind of like a pull parser. Unfortunately
these same modules have methods to return data from the HEADER (eg.
sequence_name), which return undef if you haven't read the first feature
My approach was to detect if the file handle was open for reading in
_initialize(), so that I could parse the header before the first
invocation of next_feature(), so that those HEADER-related methods would
return the correct values no matter when called. It also makes the
next_feature() implementation cleaner. The mode() detection is needed as
the file/handle could actually be for write_feature() instead.
If this is silly, I'll gladly accept advice for alternatives :-)
A related question: the header of a .ptt file has a line describing how
many features are to follow after the header. How does this fit into the
Bio::FeatureIO model? I guess I have to buffer up all the
write_feature() calls, detect when the FeatureIO object is destroyed/out
of scope, and then write the header and buffered features out?
Any advice appreciated,
Dr Torsten Seemann http://www.vicbioinformatics.com
Victorian Bioinformatics Consortium, Monash University, Australia
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