[Jprogramming] val__u in adverb and conjunction

[Henry Rich]

It looks like an error in the interpreter, but one you can work around.

The interpreter scans the text of the entity looking for the variables
m. n. u. v. m n u v
and if it doesn't find any, it assumes that x and y actually mean
u and v.  It apparently doesn't recognize val__u as being a reference
to u, so it translates x and y into u and v; in a1, for example, this
makes y undefined, because there is no v operand to the conjunction.

Before J6 you would have had to have a line like
u =. u.
which would alert the interpreter that u. is used.  Now you have
to make sure that u or v appears by itself somewhere in your
entity.  One way is

   a4 =. 1 : 'if. do. u else. y+val__u end.'

Maybe Gosi was right, and we should get rid of the old-form
modifiers for J6.

Henry Rich



> -----Original Message-----
> From: programming-bounces at jsoftware.com 
> [mailto:programming-bounces at jsoftware.com] On Behalf Of Mikl Kurkov
> Sent: Saturday, April 01, 2006 6:15 AM
> To: programming at jsoftware.com
> Subject: [Jprogramming] val__u in adverb and conjunction
> 
> I want to use numbered locale as a parameter for adverb and 
> conjunction.
> But I stucked with problem, that sometimes I'm allowed to use 
> val__u, and  
> sometimes not.
> I worked out that this can be avoided by assigning u value to 
> another  
> local variable.
> But I want to understand why it's impossible to just use val__u.
> 
> NB. Test code
> coclass 'test'
> create =: 3 : 'val =: 20'
> destroy =: codestroy
> 
> cocurrent 'base'
> t =: '' conew 'test'
> a1 =: 1 : 'y + val__u'
> a2 =: 1 : 'y + val__u1 [ u1 =. u'
> c1 =: 2 : 'y + val__u + val__v'
> c2 =: 2 : 'y + val__u + v'
> 
> t a1 10
> |value error: y
> |       y+val__u
> 
> t a2 10
> 30
> 
> (t c1 t) 10
> |domain error: c1
> |   y    +val__u+val__v
> 
> NB. but next is working
> (t c2 10) 30
> 60
> 
> NB. and this one works too
> c3 =: 2 : 'y + u + val__v'
> 
> (10 c3 t) 30
> 60
> 
> NB. but this not
> c4 =: 2 : 'y + val__v'
> (10 c4 t) 30
> |domain error: c4
> |   y    +val__v
> 
> So can you explain this behaviour
> and is it better to avoid using something like val__u in adverbs and  
> conjunctions?
> 
> -- 
> Mikl
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