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Object reference not set to an instance of an object.Why doesn't .NET show which object is `null`?
...null
IL_0002: stloc.0 // s
IL_0003: ldloc.0 // s
IL_0004: callvirt System.String.get_Length
IL_0009: call System.Console.WriteLine
It is the callvirt opcode that throws the NullReferenceException and it does that when the first argument on the evaluation stack is a null...
What is the difference between inversedBy and mappedBy?
I am developing my application using Zend Framework 2 and Doctrine 2.
4 Answers
4
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Python __str__ versus __unicode__
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It depends. Because python3 does not uses unicode but instead str ;) for python 2 unicode
– Eddwin Paz
Oct 3 '17 at 1:04
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Does const mean thread-safe in C++11?
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Two expression evaluations conflict if one of them modifies a memory location (1.7) and the other one accesses or modifies the same memory location.
[1.10/21]
The execution of a program contains a data race if it contains two conflicting actions in different threads, at least one of which is not...
Mercurial move changes to a new branch
I have a number of changes that I committed to my local repository, but have not yet been pushed. Since on a feature is taking longer than expected, I want to swap these changes onto a named branch before I push. How can I do this?
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Javascript web app and Java server, build all in Maven or use Grunt for web app?
We are doing a web application with AngularJS and we like the idea of using Bower for Dependency Management and Grunt for building, running tests etc. ( Yeoman )
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Should I pass an std::function by const-reference?
...ormance, pass by value if you are storing it.
Suppose you have a function called "run this in the UI thread".
std::future<void> run_in_ui_thread( std::function<void()> )
which runs some code in the "ui" thread, then signals the future when done. (Useful in UI frameworks where the UI...
How to declare a structure in a header that is to be used by multiple files in c?
...and include that header in the func.c?
This is the solution I like more, because it makes the code highly modular. I would code your struct as:
#ifndef SOME_HEADER_GUARD_WITH_UNIQUE_NAME
#define SOME_HEADER_GUARD_WITH_UNIQUE_NAME
struct a
{
int i;
struct b
{
int j;
}
};
#e...
Instance variables vs. class variables in Python
...ne instance anyway, it's best to make all variables per-instance, simply because they will be accessed (a little bit) faster (one less level of "lookup" due to the "inheritance" from class to instance), and there are no downsides to weigh against this small advantage.
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Why does casting int to invalid enum value NOT throw exception?
...An enum is backed by another value type (int, short, byte, etc), and so it can actually have any value that is valid for those value types.
I personally am not a fan of the way this works, so I made a series of utility methods:
/// <summary>
/// Utility methods for enum values. This static t...