Enhance Arguments to lrangeAndreas Leitgeb$Revision: 1.7 $Tcl lrange
This TIP proposes an enhancement to lrange and string range that lets them take more than one start-end index pair.
Sometimes you need to extract a non-continuous selection of elements from some list and build a new list from them. This requires the use of multiple calls to lrange and a surrounding concat to build the final list. However, since the following fails with a syntax error:
ICAgIGxyYW5nZSB7YSBiIGMgZCBlIGZ9ICAxIDMgIDUgNQ==
It would seem a reasonable extension for such a usage of lrange to return "b c d f". This would also make following pattern of usage feasible:
IGxhc3NpZ24gW2xyYW5nZSAkc29tZUxpc3QgMCAyICAxMCAxMl0gIHZhcjAgdmFyMSB2YXIyIHZhcjEwIHZhcjExIHZhcjEy
The indices should not be required to be in ascending order. This is meant such that the ranges may be overlapping at will. E.g.:
IFtscmFuZ2UgJGxpc3QgMCBlbmQgMCBlbmRdID09IFtscmVwZWF0IDIgeyp9JGxpc3Rd
This TIP does NOT change the way each range is interpreted. Reversing lists is not in the scope of this TIP.
Change the implementation of lrange to accept any odd number of arguments, with semantics (upon supply of a correct number of arguments) equivalent to:
IHByb2MgbHJhbmdlLW5ldyB7bGlzdCBhcmdzfSB7ICAgIHNldCByZXN1bHQgW2xpc3RdICAgIGZvcmVhY2gge3N0YXJ0IGVuZH0gJGFyZ3Mgew==ICAgICAgIGxhcHBlbmQgcmVzdWx0IHsqfVtscmFuZ2UgJGxpc3QgJHN0YXJ0ICRlbmRdICAgIH0=ICAgIHJldHVybiAkcmVzdWx0IH0=
Just the above mentioned procedure, at the moment.
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