Questions tagged [language-specifications]
126 questions
2
votes
1 answer
Surprising NullPointerException when using ?:
Here is a little oddity:
Integer oddity(boolean b1, boolean b2) {
return b1 ? 0 : b2 ? 1 : null;
}
This will fail with a NullPointerException if b1 and b2 are false. But this:
Integer oddity(boolean b1) {
return b1 ? 0 : null;
}
Does not throw…
Andy Turner
- 137,514
- 11
- 162
- 243
2
votes
1 answer
How to reliably detect exotic objects in JavaScript?
Is there any way to reliably whether a JavaScript object is an exotic object type, and if so what its type is?
By "exotic", I mean (for the purposes of this question) anything which is could not be created using Object.create. This includes…
cpcallen
- 1,834
- 1
- 16
- 27
2
votes
0 answers
Rails i18n inflections for error messages
Does anyone know how to define a gender for the attributes in a model? So when error messages appear I can give them a specific gender such as:
La dirección no puede estar en blanco ( Address can't be left blank) - Address has a female article in…
HFR1994
- 536
- 1
- 5
- 16
2
votes
1 answer
How to represent in Java a context-free grammar?
I have a simple grammar:
R --> R and R | R or R | atom
The only terminal we have is atom.
This is a recursive grammar because each R can be composed by nested R.
The problems I am facing are:
How to deal with recursion?
How to build a java class R…
user840718
- 1,563
- 6
- 29
- 54
2
votes
1 answer
Does constructor with optional-parameter overload it?
Here is an example of code:
public List(int capacity = defaultCapacity) {
items = new T[capacity];
}
In C# 5 Language Specification Section 1.6.7 is written:
Instance constructors can be overloaded. For example, the List
class declares two…
bot_insane
- 2,545
- 18
- 40
2
votes
1 answer
SVG path spec: moveTo and implicit lineTo
I am trying to write a little SVG path parser / normalizer and got one last issue with the spec:
As far as I understood the most commands support additional implicit commands and when they do so and are in relative mode, the "current point" will be…
Alexander Meißner
- 806
- 5
- 14
2
votes
2 answers
Using "this->" to differentiate variable names inside constructors
I recall I used to be able to do this and have it work as intended:
class foobar
{
public:
foobar(int x, int y)
{
x = x; //the variables x, y belonging to the class got correctly initialized
y = y;
}
private:
int x,…
Dennis
- 7,907
- 11
- 65
- 115
2
votes
3 answers
Does the XML Specification say anything about order of elements?
I've heard a couple times that the XML specification indicates that XML is not ordered (e.g. if you expect order, then it's not really true XML). As far as I could find, the XML specification says nothing about the order of elements; neither that…
zastrowm
- 8,017
- 3
- 43
- 63
2
votes
2 answers
Why does C# also not allow empty conditions in while loops?
Edit: I changed most of my question, because it was too long and altough my question is a request of facts, it was considered opinion based. Having said that, please read the comments where I try to explain why closing this question was wrong IMHO.…
Jordy
- 1,816
- 16
- 29
2
votes
1 answer
Semantics of bool fields in explicit layout types (ECMA-334)
I'm trying to find where in ECMA-334 (C# language specification) the following behavior is defined. The source program is as follows.
static void Main(string[] args)
{
TestStruct a = new TestStruct();
a.byteValue = 1;
TestStruct b = new…
Sam Harwell
- 97,721
- 20
- 209
- 280
1
vote
0 answers
Error struct assignment in if clause (language spec question)
I get an error which I can't explain. Can you help me?
package main
import "fmt"
type mystruct struct {
a string
}
func main() {
// ok
m := mystruct{"a"}
if m.a == "x" {
fmt.Println("is x")
}
// not ok, error…
topskip
- 16,207
- 15
- 67
- 99
1
vote
0 answers
Type Inference in Method Invocation Poly Expression within the Invocation Context with/without method chaining
I was going through this question - this triggered the following set of thoughts regarding the Type Inference:
class Song {
public Integer duration;
public String artist;
public String title;
// ... getters...
}
List playlist1 = new…
theutonium.18
- 483
- 2
- 7
1
vote
0 answers
How do deal with the "type context" rule (Java SE 16 spec §3.2) for `>` characters properly when performing lexical analysis?
I'm recently interested in writing a parser for Java language. My reference is newly released Java SE 16 spec. On 3.2. Lexical Translations, I come across this sentence but I'm not sure whether I get it:
... There is one exception: if lexical…
Javran
- 3,394
- 2
- 23
- 40
1
vote
1 answer
Coffee Can Problem in TLA+ : cannot express a task
I am trying to model the David Gries’ Coffee Can Problem in TLA+, and I am stuck at this part :
"What can you say about the color of the final remaining bean as a function of the numbers of black and white beans originally in the can?"
I don't know…
devio
- 1,147
- 5
- 15
- 41
1
vote
2 answers
Type Error in Alloy using Double In Statement
I am trying to write a predicate that will make all Bananas and Fresh Apples expensive. I am able to achieve one of the conditions but never both. I'm very new to using Alloy, any help would be very much appreciated.
Below is my code, the error is…
M5RKED
- 73
- 1
- 16