Rebol: How to use local variables with inline markup function?
2 answers
Unfortunately build-markup only uses global variables: the link text a> says: note that the variables used in tags are always global variables.
Here's a slightly looser way of doing it using an internal object ( bm-1 ) demonstrates the problem: a and b are printed with their global bm-2 values, which is a clumsy job):
a: "global-a"
b: "global-b"
bm-1: func [a b][
print build-markup "<%a%> <%b%>"
]
bm-2: func [a b][
cont: context [
v-a: a
v-b: b
]
print build-markup "<%cont/v-a%> <%cont/v-b%>"
]
bm-1 "aaa" "bbb"
bm-2 "aaa" "bbb"
REBOL3 has the word , not build-markup . It is much more flexible.
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I fixed the markup function to be able to use local contexts:
build-markup: func [
{Return markup text replacing <%tags%> with their evaluated results.}
content [string! file! url!]
/bind obj [object!] "Object to bind" ;ability to run in a local context
/quiet "Do not show errors in the output."
/local out eval value
][
content: either string? content [copy content] [read content]
out: make string! 126
eval: func [val /local tmp] [
either error? set/any 'tmp try [either bind [do system/words/bind load val obj] [do val]] [
if not quiet [
tmp: disarm :tmp
append out reform ["***ERROR" tmp/id "in:" val]
]
] [
if not unset? get/any 'tmp [append out :tmp]
]
]
parse/all content [
any [
end break
| "<%" [copy value to "%>" 2 skip | copy value to end] (eval value)
| copy value [to "<%" | to end] (append out value)
]
]
out
]
Here are some examples of use:
>> x: 1 ;global
>> context [x: 2 print build-markup/bind "a <%x%> b" self]
"a 2 b"
>> print build-markup/bind "a <%x%> b" context [x: 2]
"a 2 b"
+1
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