1Types(3) User Contributed Perl Documentation Types(3)
2
6 PDL::Types - define fundamental PDL Datatypes
7
9 use PDL::Types;
10 $pdl = ushort( 2.0, 3.0 );
12 print "The actual c type used to store ushort's is '" .
13 $pdl->type->realctype() . "'\n";
14 The actual c type used to store ushort's is 'unsigned short'
15
17 Internal module - holds all the PDL Type info. The type info can be
18 accessed easily using the "PDL::Type" object returned by the type
19 method.
20 Skip to the end of this document to find out how to change the set of
22 types supported by PDL.
23
25 A number of functions are available for module writers to get/process
26 type information. These are used in various places (e.g. "PDL::PP",
27 "PDL::Core") to generate the appropriate type loops, etc.
28 typesrtkeys
30 Returns an array of keys of typehash sorted in order of type complexity
31 pdl> @typelist = PDL::Types::typesrtkeys;
33 pdl> print @typelist;
34 PDL_B PDL_S PDL_US PDL_L PDL_IND PDL_LL PDL_F PDL_D
35 ppdefs
37 Returns an array of pp symbols for all real types. This informs the
38 default "GenericTypes" for "pp_def" functions, making support for
39 complex types require an "opt-in".
40 pdl> print PDL::Types::ppdefs
42 B S U L N Q F D
43 ppdefs_complex
45 Returns an array of pp symbols for all complex types.
46 pdl> print PDL::Types::ppdefs_complex
48 G C
49 ppdefs_all
51 Returns an array of pp symbols for all types including complex.
52 pdl> print PDL::Types::ppdefs_all
54 B S U L N Q F D G C
55 typefld
57 Returns specified field ($fld) for specified type ($type) by querying
58 type hash
59 PDL::Types::typefld($type,$fld);
61 pdl> print PDL::Types::typefld('PDL_IND',realctype)
63 long
64 mapfld
66 Map a given source field to the corresponding target field by querying
67 the type hash. This gives you a way to say, "Find the type whose
68 $in_key is equal to $value, and return that type's value for $out_key.
69 For example:
70 # Does byte type use nan?
72 $uses_nan = PDL::Types::mapfld(byte => 'ppforcetype', 'usenan');
73 # Equivalent:
74 $uses_nan = byte->usenan;
75 # What is the actual C type for the value that we call 'long'?
77 $type_name = PDL::Types::mapfld(long => 'convertfunc', 'realctype');
78 # Equivalent:
79 $type_name = long->realctype;
80 As you can see, the equivalent examples are much shorter and legible,
82 so you should only use mapfld if you were given the type index (in
83 which case the actual type is not immediately obvious):
84 $type_index = 4;
86 $type_name = PDL::Types::mapfld($type_index => numval, 'realctype');
87 typesynonyms
89 return type related synonym definitions to be included in pdl.h . This
90 routine must be updated to include new types as required. Mostly the
91 automatic updating should take care of the vital things.
92 datatypes_header
94 return C header text for pdl.h and pdlsimple.h.
95
97 This module declares one class - "PDL::Type" - objects of this class
98 are returned by the type method of an ndarray. It has several methods,
99 listed below, which provide an easy way to access type information:
100 Additionally, comparison and stringification are overloaded so that you
102 can compare and print type objects, e.g.
103 $nofloat = 1 if $pdl->type < float;
105 die "must be double" if $type != double;
106 For further examples check again the type method.
108 enum
110 Returns the number representing this datatype (see get_datatype).
111 symbol
113 Returns one of 'PDL_B', 'PDL_S', 'PDL_US', 'PDL_L', 'PDL_IND',
114 'PDL_LL', 'PDL_F' or 'PDL_D'.
115 ctype
117 Returns the macro used to represent this type in C code (eg
118 'PDL_Long').
119 ppsym
121 The letter used to represent this type in PP code code (eg 'U' for
122 ushort).
123 realctype
125 The actual C type used to store this type.
126 shortctype
128 The value returned by "ctype" without the 'PDL_' prefix.
129 badvalue
131 The special numerical value used to represent bad values for this
132 type. See badvalue routine in PDL::Bad for more details.
133 isnan
135 Given a string representing a C value, will return a C expression
136 for this type that indicates whether that value is NaN.
137 floatsuffix
139 The string appended to floating-point functions for this floating-
140 point type. Dies if called on non-floating-point type.
141 orig_badvalue
143 The default special numerical value used to represent bad values
144 for this type. (You can change the value that represents bad values
145 for each type during runtime.) See the orig_badvalue routine in
146 PDL::Bad for more details.
147
149 You can change the types that PDL knows about by editing entries in the
150 definition of the variable @types that appears close to the top of the
151 file Types.pm.PL (i.e. the file from which this module was generated).
152 Format of a type entry
154 Each entry in the @types array is a hash reference. Here is an example
155 taken from the actual code that defines the "ushort" type:
156 {
158 identifier => 'US',
159 onecharident => 'U', # only needed if different from identifier
160 pdlctype => 'PDL_Ushort',
161 realctype => 'unsigned short',
162 ppforcetype => 'ushort',
163 usenan => 0,
164 packtype => 'S*',
165 defaultbadval => 'USHRT_MAX',
166 real=>1,
167 integer=>1,
168 unsigned=>1,
169 },
170 Before we start to explain the fields please take this important
172 message on board: entries must be listed in order of increasing
173 complexity. This is critical to ensure that PDL's type conversion works
174 correctly. Basically, a less complex type will be converted to a more
175 complex type as required.
176 Fields in a type entry
178 Each type entry has a number of required and optional entry.
179 A list of all the entries:
181 • identifier
183 Required. A short sequence of upercase letters that identifies this
185 type uniquely. More than three characters is probably overkill.
186 • onecharident
188 Optional. Only required if the "identifier" has more than one
190 character. This should be a unique uppercase character that will
191 be used to reference this type in PP macro expressions of the
192 "TBSULFD" type. If you don't know what I am talking about read the
193 PP manpage or ask on the mailing list.
194 • pdlctype
196 Required. The "typedefed" name that will be used to access this
198 type from C code.
199 • realctype
201 Required. The C compiler type that is used to implement this type.
203 For portability reasons this one might be platform dependent.
204 • ppforcetype
206 Required. The type name used in PP signatures to refer to this
208 type.
209 • usenan
211 Required. Flag that signals if this type has to deal with NaN
213 issues. Generally only required for floating point types.
214 • packtype
216 Required. The Perl pack type used to pack Perl values into the
218 machine representation for this type. For details see "perldoc -f
219 pack".
220 • integer
222 Required. Boolean - is this an integer type?
224 • unsigned
226 Required. Boolean - is this an unsigned type?
228 • real
230 Required. Boolean - is this a real (not complex) type?
232 • realversion
234 String - the real version of this type (e.g. cdouble -> 'D').
236 • complexversion
238 String - the complex version of this type (e.g. double -> 'C').
240 Also have a look at the entries at the top of Types.pm.PL.
242 The syntax is not written into stone yet and might change as the
244 concept matures.
245 Other things you need to do
247 You need to check modules that do I/O (generally in the IO part of the
248 directory tree). In the future we might add fields to type entries to
249 automate this. This requires changes to those IO modules first though.
250 You should also make sure that any type macros in PP files (i.e.
252 "$TBSULFD...") are updated to reflect the new type. PDL::PP::Dump has a
253 mode to check for type macros requiring updating. Do something like
254 find . -name \*.pd -exec perl -Mblib=. -M'PDL::PP::Dump=typecheck' {} \;
256 from the PDL root directory after updating Types.pm.PL to check for
258 such places.
259perl v5.34.0 2021-08-16 Types(3)