file ... is readable

operator

Return type:
Switch
Returns:
True if the file is readable, false otherwise.
Syntax
file string-expression (is | isnt) readable


Purpose

The file ... is readable test is used to determine if the system path named by the string expression exists and is readable by the OmniMark program. This is useful to avoid a program error when reading a file. Using isnt instead of is will reverse the results.

For example, the following program shows how file ... is readable is used to avoid attempting to read a file that cannot be be read: 

  find "\input{" [any \ "}"]+ => filename "}"
     assert file filename is readable message "File " || filename || " does not exist."
  
     submit file filename

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