A tag for questions related to the design of any aspect of programming languages.
Questions tagged [language-design]
1363 questions
52
votes
1 answer
Why are await and async valid variable names?
I was experimenting with how / is interpreted when around different keywords and operators, and found that the following syntax is perfectly legal:
// awaiting something that isn't a Promise is fine, it's just strange to do:
const foo = await…
CertainPerformance
- 356,069
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52
votes
13 answers
What are practical guidelines for evaluating a language's "Turing Completeness"?
I've read "what-is-turing-complete" and the wikipedia page, but I'm less interested in a formal proof than in the practical implications of requirements for being Turing Complete.
What I'm actually trying to decide is if the toy language I've just…
AShelly
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51
votes
7 answers
C# static member "inheritance" - why does this exist at all?
In C#, a superclass's static members are "inherited" into the subclasses scope. For instance:
class A { public static int M() { return 1; } }
class B : A {}
class C : A { public new static int M() { return 2; } }
[...]
A.M(); //returns 1
B.M();…
Eamon Nerbonne
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51
votes
9 answers
Why don't languages raise errors on integer overflow by default?
In several modern programming languages (including C++, Java, and C#), the language allows integer overflow to occur at runtime without raising any kind of error condition.
For example, consider this (contrived) C# method, which does not account for…
Jon Schneider
- 25,758
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50
votes
13 answers
C++ iterators considered harmful?
At the Boost library conference today, Andrei Alexandrescu, author of the book Modern C++ Design and the Loki C++ library, gave a talk titled "Iterators Must Go" (video, slides) about why iterators are bad, and he had a better solution.
I tried to…
Unknown
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49
votes
32 answers
Why are many languages case sensitive?
Why are many languages case sensitive?
Is it simply a matter of inheritance? C++ is case-sensitive because C is, Java is case-sensitive because C++ is, etc.? Or is there a more pragmatic reason behind it?
Yuvi
- 4,447
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49
votes
4 answers
Why aren't there compiler-generated swap() methods in C++0x?
C++ compilers automatically generate copy constructors and copy-assignment operators. Why not swap too?
These days the preferred method for implementing the copy-assignment operator is the copy-and-swap idiom:
T& operator=(const T& other)
{
T…
jamesdlin
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47
votes
5 answers
Where are expressions and constants stored if not in memory?
From C Programming Language by Brian W. Kernighan
& operator only applies to objects in memory: variables and array
elements. It cannot be applied to expressions, constants or register
variables.
Where are expressions and constants stored if…
Aquarius_Girl
- 21,790
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47
votes
11 answers
Why didn't C have a boolean data type prior to C99?
I realise you can just #define some integers, but why didn't C have a dedicated boolean data type before C99?
It's such a common occurence in programming and logic, I don't understand the absense of an explicit type and notation.
xyz
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46
votes
4 answers
Why are there two assignment operators, `<-` and `->` in R?
I know how to use <- and ->, and there are several writeups on the difference between equals assignment & arrow assignment, but I don't know when to prefer -> over <-.
It seems the community has coalesced around using <- for assignment.
Neither the…
Haleemur Ali
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44
votes
1 answer
Why isn't __new__ in Python new-style classes a class method?
The Changelog for Python 2.2 (where new-style classes were introduced) says the following about the __new__ function:
__new__ is a static method, not a class method. I initially thought it would have to be a class method, and that's why I added the…
Dolda2000
- 25,216
- 4
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- 92
44
votes
3 answers
Why was IEnumerable made covariant in C# 4?
In earlier versions of C# IEnumerable was defined like this:
public interface IEnumerable : IEnumerable
Since C# 4 the definition is:
public interface IEnumerable : IEnumerable
Is it just to make the annoying casts in LINQ expressions…
soc
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44
votes
1 answer
Why do C++ templates use the angle bracket syntax?
The titular question refers to the design decisions in the C++ standard that introduced templates around 1990.
Why did the designers use <> (angle brackets) instead of, say, () (round brackets)? Doing so would have saved lots of programmers from…
shuhalo
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44
votes
6 answers
I don't understand why we need the 'new' keyword
I am new to C#, from a C++ background. In C++ you can do this:
class MyClass{
....
};
int main()
{
MyClass object; // this will create object in memory
MyClass* object = new MyClass(); // this does same thing
}
Whereas, in C#:
class…
user6528398
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44
votes
2 answers
Why did Matz choose to make Strings mutable by default in Ruby?
It's the reverse of this question: Why can't strings be mutable in Java and .NET?
Was this choice made in Ruby only because operations (appends and such) are efficient on mutable strings, or was there some other reason?
(If it's only efficiency,…
Seth Tisue
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