NAME
BoutrosLab::TSVStream:WriterSYNOPSIS
$class->writer( ... );
# ($class will use the role BoutrosLab::TSVStream which will provide
# the writer method, that method will return a Writer object with:
# ...
# return BoutrosLab::TSVStream::Writer->new(
# handle => $fd, # (required)
# class => $class, # (required) class
# file => $file, # (optional) used (as filename) in error messages
# header => $str, # (optional) one of: write skip (default 'write' unless append)
# append => 1, # (optional) if true:
# # file is opened for append (if stream not provided)
# # header defaults to 'skip'
# );
while (my $record = $writer->read) {
# ... $record is a $class object
# ... use $record->field1, $record->field2, etc. - all of the methods of $class object
}DESCRIPTION
This object provides an iterator to read through the lines of a data stream ($fd), converting each from a line with tab separated fields into an object of a class ($classs) that has attributes for those fields.
Usually, the data stream will start with a line that has the fieldnames in a tab separated list, and the rest of the stream has lines that contain the field values in a tab separated list.
Any error diagnostics will refer to the stream using the $file filename if it is provided.
The $class class will have a class method named _fields that provides a ref to array of string listing the fields to .be written and their order.
A class $class object must be provided for each line. The object will be re-formatted into tab separated format and written out.
If header is provided, it can be 'write', or 'skip'. This controls what is done to the handle initially.
If 'write' is specified, a header line is written to the stream containing the field names in tab separated format before writing any explicitly provided objects. This is the default. If 'skip' is specified, no header is written.
If 'skip' is specified, the stream is not checked for a header line. (You would use this option either if the file does not have a header line, or if you are scanning from the middle of a file handle that is no longer at the start of the file.)
ATTRIBUTES
handle - the filehandle to be read
file - the name of the stream, usually a filename, for diagnostic purposes
class - the class that records transformed into
fields - list of field names, usually provided by class
handle, file, class and fields are provided by the ...::IO::Role::Base::Fixed role
append - (optional) boolean to cause writes to append to the stream, causes header to default to 'skip'
header - 'write', or 'skip' (default 'write' normally, 'skip' if 'append' is enabled)
The 'write' setting causes the first line of the stream to be written with a list of field names. This is the default unless the append option is set.
If the 'skip' setting is provided, the stream writing will start with a data value. Use this either for writing a stream that is not supposed to have a header line, or else to append additional values to an existing file (of the same type of course). This must normally be asked for explicitly, but it is the default if the append option is set.
BUILDARGS
The BUILDARGS method opens a handle if only a file is provided.
BUILD
The BUILD method handles any requirements for reading and processing a header line.
METHODS
write - read a line to the stream from a class element
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AUTHOR
John Macdonald - Boutros Lab
ACKNOWLEDGEMENTS
Paul Boutros, Phd, PI - Boutros Lab
The Ontario Institute for Cancer Research