New values for the OPTIONS instruction
/******************************************************************************
* This file is part of The Unicode Tools Of Rexx (TUTOR) *
* See https://rexx.epbcn.com/TUTOR/ *
* and https://github.com/JosepMariaBlasco/TUTOR *
* Copyright © 2023-2025 Josep Maria Blasco <josep.maria.blasco@epbcn.com> *
* License: Apache License 2.0 (https://www.apache.org/licenses/LICENSE-2.0) *
******************************************************************************/OPTIONS DEFAULTSTRING
OPTIONS DEFAULTSTRING default, where
default can be one of BYTES,
CODEPOINTS, GRAPHEMES,
TEXT or NONE. This affects the
semantics of numbers and unsuffixed strings, i.e.,
"string", without an explicit B, X, Y, P, T or U suffix. If
default is NONE, numbers and strings are not converted (i.e.,
they are handled as default Rexx numbers and strings). In the other
cases, numbers and strings are transformed to the corresponding type.
For example, if OPTIONS DEFAULTSTRING TEXT is in effect,
"string" will automatically be a TEXT string, as if
"string"T had been specified, i.e., "string"
will be composed of extended grapheme clusters, and will be
automatically normalized to the NFC Unicode normalization form if
needed; if OPTIONS DEFAULTSTRING GRAPHEMES is in effect,
"string" will automatically be a GRAPHEMES string, as if
"string"G had been specified, i.e., "string"
will be composed of extended grapheme clusters, with no automatical
normalization; , and if OPTIONS DEFAULTSTRING CODEPOINTS is in effect,
12.3 will automatically be a CODEPOINTS string, as if
CODEPOINTS(12.3) had been specified.
By default, RXU works as if OPTIONS DEFAULTSTRING TEXT had been specified.
Note. Currently, OPTIONS DEFAULTSTRING does not apply to variable and constant symbols. This will be fixed in a future release.
Implementation restriction: This is currently a global option. You can change it inside a procedure, and it will apply globally, not only to the procedure scope.
Examples.
Say Stringtype("string") -- BYTES (the default)
Options Defaultstring CODEPOINTS
Say Stringtype("string") -- CODEPOINTS
Say Stringtype(1024) -- CODEPOINTS too
Say Stringtype("12"X) -- BYTES: X, B and U strings are always BYTES strings
Say Stringtype("string"T) -- TEXT (Explicit suffix)
Implementation notes:
RXU translates an unsuffixed string "string" to the
following expression:
(U:Default("string"))
Default is a helper routine defined in
Unicode.cls, and U is a suitable namespace for
Unicode.cls. The Default routine implements
the current OPTIONS DEFAULTSTRING setting.
OPTIONS COERCIONS
OPTIONS COERCIONS behaviour, where
behaviour can be one of PROMOTE,
DEMOTE, LEFT, RIGHT
or NONE. This instruction determines the behaviour of
the language processor when a binary operation is attempted in which the
operators are of different string types, for example, when a BYTES
string is contatenated to a TEXT string, or when a CODEPOINTS number is
added to a BYTES number.
- When behaviour is NONE a Syntax error will be raised.
- When behaviour is PROMOTE, the result of the operation will have the type of the highest operand (i.e., TEXT when at least one of the operands is TEXT, or else CODEPOINTS when at least one of the operands is CODEPOINTS, or BYTES in all other cases).
- When behaviour is DEMOTE, the result of the operation will have the type of the lowest operand (i.e., BYTES when at least one of the operands is BYTES, or else CODEPOINTS when at least one of the operands is CODEPOINTS, or TEXT in all other cases).
- When behaviour is LEFT, the result of the operation will have the type of the left operand.
- When behaviour is RIGHT, the result of the operation will have the type of the right operand.
Currently, OPTIONS COERCIONS is implemented for concatenation, arithmentic and logical operators only.
By default, RXU works as if OPTIONS COERCIONS PROMOTE had been specified.
Note. This variant of the OPTIONS instruction is highly experimental. Its only purpose is to allow experimentation with implicit coercions. Once a decision is taken about the preferred coercion mechanism, it will be removed.
Implementation restriction: This is a global option. You can change it inside a procedure, and it will apply globally, not only to the current scope.
Examples.
Code could not be displayed because of the following error:
2 *-* Say Stringtype( "Left"B || "Right"P ) -- CODEPOINTS
Error 15 in /media/sf_C/Dropbox/Webs/ssl/rexx.epbcn.com/TUTOR/doc/options/readme.md, line 82: Invalid hexadecimal or binary string.
Error 15.4: Only 0, 1, and whitespace characters are valid in a binary string; found "L".
Implementation notes
The RXU Rexx Preprocessor for Unicode implements the OPTIONS instruction in the following way: when an OPTIONS instruction is encountered, say
OPTIONS optiona optionb
the preprocessor transforms it into
Do; !Options = optiona optionb; Call !Options !Options; Options !Options; End
!OPTIONS is a routine defined in
Unicode.cls.