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Access lapply index names inside FUN
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Unfortunately, lapply only gives you the elements of the vector you pass it.
The usual work-around is to pass it the names or indices of the vector instead of the vector itself.
But note that you can always pass in extra arguments to the function, so the following works:
x <- list(a=11,b=12,c...
Undo working copy modifications of one file in Git?
After the last commit, I modified a bunch of files in my working copy, but I want to undo the changes to one of those files, as in reset it to the same state as the most recent commit.
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How do I add a delay in a JavaScript loop?
...tion is non-blocking and will return immediately. Therefore your loop will iterate very quickly and it will initiate 3-second timeout triggers one after the other in quick succession. That is why your first alerts pops up after 3 seconds, and all the rest follow in succession without any delay.
You...
Passing an array by reference
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It's a syntax for array references - you need to use (&array) to clarify to the compiler that you want a reference to an array, rather than the (invalid) array of references int & array[100];.
EDIT: Some clarificati...
Advantages of Antlr (versus say, lex/yacc/bison) [closed]
...sually translators (such as a subset of EDIF streamed into an EDA app). Additionally, I've had to support code based on lex/yacc grammars dating back decades. So I know my way around the tools, though I'm no expert.
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Does “untyped” also mean “dynamically typed” in the academic CS world?
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Yes, this is standard practice in academic literature. To understand it, it helps to know that the notion of "type" was invented in the 1930s, in the context of lambda calculus (in fact, even earlier, in the context of set theory). Since then, a whole branch of computa...
DateTime “null” value
I've been searching a lot but couldn't find a solution. How do you deal with a DateTime that should be able to contain an uninitialized value (equivalent to null)? I have a class which might have a DateTime property value set or not. I was thinking of initializing the property holder to DateTime.Min...
What's the difference between a proc and a lambda in Ruby?
...g lambda {} gives you a proc that checks the number of arguments passed to it. From ri Kernel#lambda:
Equivalent to Proc.new, except the resulting Proc objects check the number of parameters passed when called.
An example:
p = Proc.new {|a, b| puts a**2+b**2 } # => #<Proc:0x3c7d28@(irb)...
Solutions for INSERT OR UPDATE on SQL Server
...can use something like this:
begin tran
if exists (select * from table with (updlock,serializable) where key = @key)
begin
update table set ...
where key = @key
end
else
begin
insert into table (key, ...)
values (@key, ...)
end
commit tran
or
begin tran
update table with (serial...
How do I implement basic “Long Polling”?
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It's simpler than I initially thought.. Basically you have a page that does nothing, until the data you want to send is available (say, a new message arrives).
Here is a really basic example, which sends a simple string afte...