If you don't like reading long post, just read question #4 that synthetize the
previous questions...
**1\. What does it mean for a template /macro to have ``typed`` and ``untyped``
parameters at the same time?**
Can the compiler anticipate the semantic analysis phase for some arguments
while not considering others?
For instance, in the following template, `typ` would be checked to be a
`string` while the compiler does not care about the validity of `code`...
template dsl(typ: static[string]; code: untyped) =
...
Run
**2\. Is it possible to have default parameter values in template?**
The preceding example becomes:
template dsl(typ: static[string] = "quick"; code: untyped) =
...
Run
I've tried it but I can't have both blocks below working:
dsl "fast":
# Use fast algorithm
echo "fast"
dsl:
# Use quick algorithm
echo "quick"
Run
**3\. Identifier construction in template**
Now I want to call different procedures depending on `typ` value. According to
the [indentifier
construction](https://nim-lang.org/docs/manual.html#templates-identifier-construction)
section of the manual, backticks is the way to go.
template dsl(typ: static[string]; code: untyped) =
`typ Algo`()
...
dsl "fast":
# Call `fastAlgo`()
Run
But the name of the procedure is interpreted as `"fast"Algo` that does not
exist. Is it possible to remove the string quotes?
**4\. Why all this?**
I have multiple bindings to different algorithms and I want to let the user
select the one to use. When none is selected, there is a default one. The best
I was able to write is below that does not compile when `typ` is not specified.
proc fastAlgo() =
echo "fastAlgo"
proc quickAlgo() =
echo "quickAlgo"
template dsl(typ: untyped; code: untyped) =
`typ Algo`()
code
dsl fast:
# Call `fastAlgo`()
echo "running"
dsl: <<=== type mismatch: got <void> but expected one of: template dsl(typ:
untyped; code: untyped) first type mismatch at position: 2 missing parameter:
code
# Call `quickAlgo`()
echo "running too"
Run
How would you do this?
