1IDL(3)                User Contributed Perl Documentation               IDL(3)
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NAME

6       PDL::IO::IDL -- I/O of IDL Save Files
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DESCRIPTION

9       PDL::IO::IDL allows you to read and write IDL(tm) data files.
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11       Currently, only reading is implemented.  Scalars, arrays, and
12       structures are all supported.  Heap pointers, compiled code, and
13       objects are not supported.  Of those three, only heap pointers are
14       likely to be supported in the future.
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16       This code was not developed by RSI, makers of IDL.
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NOTES

19       These things seem to work:
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21       BYTE, SHORT, LONG, FLOAT, and DOUBLE numeric types and arrays
22          All of these types seem to work fine.  The corresponding variable is
23          stored as a PDL in the hash element with the same name as the
24          original variable in the file.  Arrays are byteswapped as needed and
25          are read in so that the dim list has the same indexing order within
26          PDL as it did within IDL.
27
28       STRINGs and arrays of STRINGs
29          String types are stored as Perl list refs, in the hash element with
30          the same name as the original variable in the file.
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32       Structures
33          Structures are stored as hash refs.  The elements of the hash may be
34          accessed as values within the hash.
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36       Common blocks
37          Variables that are notated as being in a common block are read as
38          normal.  Common-block names are collected in the special hash value
39          '+common', which contains a hash each keyword of which is the name
40          of a common block and each value of which is an array of variable
41          names.
42
43       These things are known to be not working and may one day be fixed:
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45       COMPLEX numbers
46          These could be implemented as 2-arrays or as PDL::Complex values,
47          but aren't yet.
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49       PTR types
50          These could be implemented as perl refs but currently aren't.
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52       writing
53          Maybe one day -- but why bother writing a broken file format?
54          NetCDF is better.
55
56       These things are known to be not working and will probably never be
57       fixed
58
59       Compiled code
60          Decompiling IDL code is a violation of the IDL end-user license.  To
61          implement this, someone who does not hold an IDL license would have
62          to reverse-engineer a set of .SAV files sent to that person by
63          someone else with an IDL license.
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65       Objects
66          IDL objects contain compiled code.
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FUNCTIONS

69   ridl
70       $x = ridl("foo.sav");
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72       Read an IDL save file from a file.
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74       Upon successful completion, $x is a hash ref containing all of the
75       variables that are present in the save file, indexed by original
76       variable name.
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78       IDL identifiers are case insensitive; they're all converted to upper-
79       case in the hash that gets returned.  This may be adjustable at a
80       future date.  Furthermore, because IDL identifiers can't contain
81       special characters, some fields that start with '+' are used to store
82       metadata about the file itself.
83
84       Numeric arrays are stored as PDLs, structures are stored as hashes, and
85       string and structure arrays are stored as perl lists.  Named structure
86       types don't exist in perl in the same way that they do in IDL, so named
87       structures are described in the 'structs' field of the global metadata.
88       Anonymous structures are treated as simple hashes.  Named structures
89       are also simple hashes, but they also contain a field '+name' that
90       refers to the name of the structure type.
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AUTHOR, LICENSE, NO WARRANTY

93       THIS CODE IS PROVIDED WITH NO WARRANTY and may be distributed and/or
94       modified under the same terms as PDL itself.
95
96       This code is based on the analysis of the IDL save file format
97       published by Craig Markwardt in 2002.
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99       IDL is a trademark of Research Systems Incorporated (RSI).  The PDL
100       development team, and authors of this code, are not affiliated with
101       RSI.
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105perl v5.34.0                      2022-02-28                            IDL(3)
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