Zugg Software :: View topic

Posted: Tue Jul 13, 2010 2:35 am

I just upgraded from 3.20 to 322 today, and code that worked fine in 3.20 was giving me issues. I've sorted out the cause.

Magician Joined: 02 Feb 2004 Posts: 364 Location: USA

It probably interpreted it as something like db.key or item.list. Using concat should fix the issue.

Posted: Tue Jul 13, 2010 9:58 am

Or just putting a ~ in front of the first '.'... quicker that way. GS is probably right on this, though, but it should be a bug as there is no variable being called with @...

Charneus

Wizard Joined: 17 Jun 2006 Posts: 1201

You should try using MXP coloring. It's a lot nicer with more color options and you can do things like strong, italics, underline, and so on.

It's really easy.

Posted: Tue Jul 13, 2010 5:59 pm

Wizard Joined: 22 Mar 2007 Posts: 2320

I don't suppose you can only allow it on specific functions which _can_ return a table? I suppose the code can't be easily be made smart enough to only do it on certain functions, and could lead to confusion, as well.

Posted: Tue Jul 13, 2010 10:19 pm

No, that doesn't really work either and I really hate to make the parser aware of the actual function being executed (that breaks the modularity between the lexer and the parser). Also, somebody is bound to do something like this:

Posted: Tue Jul 13, 2010 10:50 pm

The problem with that logic, Zugg, is that while it /is/ after a function call, it's also after a function that has properly closed its arguments with parentheses... and since CMUD wouldn't allow %db(@Stuff).key), why in the world would it just think 'Oh, %ansi(green)... must be a %db call!'?

Just curious on this because it doesn't make too much sense to me otherwise.

Charneus

SubAdmin Joined: 18 Nov 2001 Posts: 5182

About the only thing I see having a dot notation on functions be useful for is COM calls. It seems like this is another of those cases where implicit concat is getting in the way. Perhaps a better error message would be enough to solve that part of the problem.

There are a few other things that could help in sorting out the use of dot with with functions. First consider how it works with variables.

Wizard Joined: 22 Mar 2007 Posts: 2320

Charneus, the point is that Cmud _does_ now allow %db(@table,key).otherkey. This works if the value returned by the first %db() is itself a stringlist or key-value list. It also only works (I believe) in cases where the @ is not required in front of a variable name. This is part of the new json stuff.

Vijilante, the first line is blank because there is no key "d" in the variable "a". The second line prints as it does because 1 cannot be a variable name, and besides there is no @ before the 1, so it just concatenates the 1 and .d. The third prints nothing because there is no variable named "a.d", and "a.d" does not resolve into anything else because there is no amperand before the a to make it a variable name. @{@a.d} would show something, if the variable a had a key d, whose value was the name of another variable. I'm not sure what you are trying to show with this script.

Your second script does seem to show an oddity between two dots and three dots. The issue of using %{} is because you can actually have a variable function name. Say you have a variable "a" whose value is "time". If you do: "#show %{@a}", you get the same result as if you did "#show %time". Your proposal would break that.

Posted: Wed Jul 14, 2010 5:28 pm

Yeah, Rahab is correct about the problems trying to use the %{func(param).key} syntax. That is used for indirect execution and not really for what we are trying to do here.

But Vijilante's test results were quite interesting. I didn't expect the case with two dots to work with three dots failing. I thought the code just scanned the characters before the dot to look for a valid @ or % function reference. I think it also stops looking when it sees a (param) list since that often indicates a COM reference.

Definitely some issues for me to look at in this part of the parser. It's very complex and difficult to work on without having side effects that break other stuff, so I have to be really careful with it.

In fact, the line that checks for the % character and allows the dot after a function was previously there but commented out. Almost like I had played with this in the past at some point but then decided it just didn't work. Too bad I don't remember why.

In the case of variables, I think the DOT operator is doing some stuff at run-time where if the variable doesn't exist, it falls back to doing an append. I might be able to do something similar with functions where it actually tests the value on the runtime stack to see if it's a database variable or not. That would make it more consistent with how variables work, even though I tend to dislike parsing syntax that changes behavior at runtime. But since I already do it with variables (and I'm not changing that), then I might as well do the same thing for functions.

SubAdmin Joined: 18 Nov 2001 Posts: 5182

Rahab, I don't wish to seem argumentative, but there are a few things you missed. Here try this one:

Posted: Wed Aug 18, 2010 10:21 pm

Btw, I have dealt with this issue by checking the %function to see if it can return a DB variable. So %list(string).key is allowed, but %ansi(string).key will properly perform the implicit concat of the ".key" string.

I also fixed the issue with multiple dots. I also fixed another related bug having a space (or other nonvalid key value) after the dot.

So the command in the original post will work in the new version. And the only time you'll have trouble with explicit concat is using .key after a function that can return a list or table. Here is the list of functions that can return a list/table:

additem
addkey
db
dbitems
dbkeys
dbvalues
delitem
delkey
delnitem
dups
item
json
list
pop
push
replaceitem
sort

Novice Joined: 09 Sep 2006 Posts: 44

Off the top of my head, %countlist should probably be added to the list of viable db functions.

Can't think of any others at the moment.

Posted: Thu Aug 19, 2010 3:25 pm

I think your mistaken Derar. This isn't a list of functions that can use db variables but a list of function that can return a list or table. %countlist will always return a number.

Novice Joined: 09 Sep 2006 Posts: 44

I think you're thinking of %numitems, actually.

From #HELP countlist:

"Count the number of times each item appears in a string list and return a database record with the items as key properties, and the count of each item as the value of the key."

Posted: Fri Aug 20, 2010 4:49 pm

Yep, Derar is correct. I've added %countlist to the list.