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The open function initializes access to a port according to specified parameters. The function can be supplied with a filename, a URL, or an object. In addition, there are several refinements that will affect the open operation or the access to the port's data.
The simplest method of using open is to provide it with a filename or URL as its argument. In the example below, a file port is opened:
fp: open %file.txt
The fp variable refers to the port. If the port did not open, an error will occur. If necessary, the error can be caught with the try function.
By default the file is opened as buffered. This means that the file is accessed and modified in memory and changes to the file are not written out until the port is closed or updated.
For files, the open function will automatically create the file if it does not already exist.
close open %somefile.txt if exists? %somefile.txt [print "somefile exists"] somefile exists
The /new refinement can be used to overwrite an existing file.
write %somefile.txt "text in some file" print read %somefile.txt text in some file
close insert open/new %somefile.txt "new data" print read %somefile.txt new data
The open function accepts a number of refinements that can be used to modify its operation:
|/binary||port data is binary|
|/string||port data is text, translate all line terminators|
|/with||specify an alternate line termination|
|/lines||handle data a line at a time or as a block of lines|
|/direct||do not buffer the port|
|/new||create or recreate the target of the port|
|/read||open for read only operation|
|/write||open for write only operation|
|/no-wait||do not wait for data|
|/skip||skip part of the data|
|/allow||specify protection attributes of files|
|/custom||allow special refinements|
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