Forums

Problem parsing square brackets in string literals

General discussion about Cobra. Releases and general news will also be posted here.
Feel free to ask questions or just say "Hello".

Problem parsing square brackets in string literals

Postby khjklujn » Sat Feb 23, 2008 8:11 am

Cobra 0.7.3, Mono 1.2.6

The following program fails with "error: Expecting an expression" in line 3.
class Program
def main is shared
t = '0123['
print t.indexOf('[')

The workaround I am using is:
class Program
def main is shared
t as String = sharp' "0123[" '
print t.indexOf(sharp' "[" ')
khjklujn
 
Posts: 29

Re: Problem parsing square brackets in string literals

Postby Dafra » Sat Feb 23, 2008 9:12 am

I've got the same problem each time there is a square bracket in a string. Maybe Cobra believes they are regexs ?
I use ns'123[' (no substitution) or r'123[' (raw). You should try both because I don't know the difference.
Dafra
 
Posts: 12

Re: Problem parsing square brackets in string literals

Postby dennis » Sat Feb 23, 2008 11:32 am

Rather than a regex, I think Cobra is probably looking for a variable substitution:

print 'Value: [foo]'


This works, for example:

a = '456'
b = '123[a]789'


I also tried escaping the bracket with a backslash or doubling the bracket. Neither worked.

t = '0123\[' # Nope
t = '0123[[' # Nope


So I think r'0123[' or ns'0123[' are the correct way.

This works, BTW (it gives '0123['):

s = '12'
t = '0[s]' + r'3['
dennis
 
Posts: 21

Re: Problem parsing square brackets in string literals

Postby Charles » Sat Feb 23, 2008 2:54 pm

You are correct that square brackets are used for interpolation. Also, you can have any kind of expression. And you can use : followed by a .NET formatting code:
print '[person.lastName], [person.firstName]'
print '[amount:N2]'

If you search for "C# string formatting" or such you'll find info on the formatting codes.

ns stands for "no substitution". It still respects \n \r \t etc. as meaning newline, carriage return, tab etc.

r stands for "raw" which is like Python's r'aoeu' and C#'s @"aoeu". All characters are literal including backslashes and brackets. Most often used for regular expressions where backslashes are common.

I've wanted \[ to work for awhile, but just haven't gotten to it. I also see that a better error message could be given to guide people.
Charles
 
Posts: 2510
Location: Los Angeles, CA


Return to Discussion

Who is online

Users browsing this forum: No registered users and 3 guests

cron