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PutAppend

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description

PutAppend[expr, "filename"] or expr >>> "filename"

appends expr to the end of the file, creating the file if it does not exist.

PutAppend[expr1, expr2, ..., "filename"]

appends a sequence of expressions, one per line.

Notes PutAppend works the same as Put, except that it preserves any existing contents of the file rather than truncating them. expr \>\>\> filename is equivalent to expr \>\>\> "filename". Returns Null on success and $Failed if the file cannot be opened.

Examples (2)

Every input below was run against the current Mathilda build and its output recorded.

Applications (2)

In[1]:= Put[x^2 + 1, "/tmp/mathilda_demo.m"]
Out[1]= Null

In[2]:= PutAppend[y, "/tmp/mathilda_demo.m"]
Out[2]= Null

Algorithm

readwrite.c - File I/O builtins (Get, Put).

Get reads Mathilda source from a file and evaluates each expression, returning the last value (used by the REPL bootstrap to load the internal .m initialization files).

Put writes one or more expressions to a file in InputForm so the

output can be read back with Get.  The parser also recognises the

infix shorthand expr >> "file" and lowers it to Put[expr, "file"].

Implementation notes

builtin_putappend shares put_common with Put, differing only in fopen mode: it opens the (last-argument) filename in "a" mode, appending each preceding expression — serialized via expr_to_string (the standard printer) plus a trailing \n — to the end of the file, creating it if absent and never truncating an existing one. PutAppend["file"] writes nothing. Open failure prints PutAppend::noopen and returns $Failed; success returns Null. ATTR_PROTECTED. The infix expr >>> "file" lowers to PutAppend[expr, "file"].

  • Protected.
  • Creates the file if it does not exist; otherwise preserves prior contents and appends new lines.
  • Returns Null on success and $Failed on I/O error.

Attributes: Protected.

References

See also: Put

Notes & additional examples

Notes

PutAppend[expr, "file"] (equivalently expr >>> "file") adds expr on a new line at the end of the file, creating the file if it does not exist.