Are there any disadvantages, caveats or bad practice warnings about using the following pattern?

    def buildString(user, name = &#39;john&#39;, age=22):
        userId = user.getUserId()
        return &quot;Name: {name}, age: {age}, userid:{userId}&quot;.format(**locals())

I had a very repetitive string generation code to write and was tempted to use this, but something about using `locals()` makes me uncomfortable. Is there any danger of unexpected behavior in this?

Edit: context

I found myself constantly writing stuff like:
    

    &quot;{name} {age} {userId} {etc}...&quot;.format(name=name, age=age, userId=userId, etc=etc)

Using locals() and format() method for strings: are there any caveats?

Hi I have a observable user$ with a lot of properties (name, title, address...)

    component{
      user$:Observerable&lt;User&gt;;
      constructor(private userService:UserService){
        this.user$ = this.userService.someMethodReturningObservable$()
      }
    }

Is there a way to use the async pipe in the html template to subscribe to it and bind it to a local variable like this

    &lt;div #user=&quot;user$ | async&quot;&gt;
      &lt;h3&gt; {{user.name}}
    &lt;/div&gt;

I know can can subscribe to it in the constructor and then unsubscribe in OnLeave/OnDestroy but I was just curious if I could use the async pipe.

Cheers

angular - using async pipe on observable&lt;Object&gt; and bind it to local variable in html

Let&#39;s say I&#39;m using `irb`, and type `a = 5`. How do I remove the definition of `a` so that typing `a` returns a `NameError`?

Some context: later I want to do this:

    context = Proc.new{}.binding
    context.eval &#39;a = 5&#39;
    context.eval &#39;undef a&#39;  # though this doesn&#39;t work.

Undefine variable in Ruby

Im trying to get the value from BrandID in one table and add it to another table. But I can&#39;t get it to work. Anybody know how to do it right?

    CREATE PROCEDURE AddBrand
    AS
    
    DECLARE 
    @BrandName nvarchar(50),
    @CategoryID int,
    @BrandID int
    
    SELECT @BrandID = BrandID FROM tblBrand 
    WHERE BrandName = @BrandName

    INSERT INTO tblBrandinCategory (CategoryID, BrandID) 
           VALUES (@CategoryID, @BrandID) 
    
    RETURN

How to declare a variable in SQL Server and use it in the same Stored Procedure

I have the following code.

    #include &lt;iostream&gt;
     
    int * foo()
    {
    	int a = 5;
    	return &amp;a;
    }
    
    int main()
    {
    	int* p = foo();
    	std::cout &lt;&lt; *p;
    	*p = 8;
    	std::cout &lt;&lt; *p;
    }

And the code is just running with no runtime exceptions!

The output was `58`

How can it be? Isn&#39;t the memory of a local variable inaccessible outside its function?


Can a local variable&#39;s memory be accessed outside its scope?

If I create a bool within my class, just something like `bool check`, it defaults to false. 

When I create the same bool within my method, `bool check`(instead of within the class), i get an error &quot;use of unassigned local variable check&quot;. Why?

Why do local variables require initialization, but fields do not?

My goal is:

 - Given a suspended thread in a Delphi-compiled 32 or 64-bit Windows program, to walk the stack (doable)
 - Given stack entries, to enumerate the local variables in each method and their values. That is, at the very least, find their address and type (integer32/64/signed/unsigned, string, float, record, class...) the combination of which can be used to find their value.

The first is fine and it&#39;s the second that this question is about. At a high level, **how do you enumerate local variables given a stack entry in Delphi?**


----------

At a low level, this is what I&#39;ve been investigating:

**RTTI:** does not list this kind of information about methods. This was not something I actually ever thought was a realistic option, but listing here anyway.

**Debug information:** Loading the debug info produced for a debug build.

 - Map files: even a detailed map file (a text-format file! Open one and have a look) does not contain local variable info. It&#39;s basically a list of addresses and source file line numbers. Great for address to file&amp;line correlation, e.g. the blue dots in the gutter; not great for more detailed information
 - Remote debugging information (RSM file) - [no known information][1] on its contents or format.
 - **TD32/TDS files:** my current line of research. They contain global and local symbols among a lot of other information.

The problems I&#39;m encountering here are:

 - There&#39;s no documentation of the TD32 file format (that I can find.)
 - Most of my knowledge of them comes from the Jedi JCL code using them (JclTD32.pas) and I&#39;m not sure how to use that code, or whether the structures there are extensive enough to show local vars. I&#39;m pretty certain it will handle global symbols, but I&#39;m very uncertain about local. There are a wide variety of constants defined and without documentation for the format, to read what they mean, I&#39;m left guessing. However, those constants and their names must come from somewhere.
 - [Source I can find using TDS info][2] does not load or handle local symbols.

If this is the right approach, then this question becomes &#39;Is there documentation for the TDS/TD32 file format, and are there any code samples that load local variables?&#39;

A code sample isn&#39;t essential but could be very useful, even if it&#39;s very minimal.


  [1]: https://stackoverflow.com/questions/10481027/remote-debug-symbol-file-format
  [2]: http://sourceforge.net/p/tds2dbg/wiki/Main_Page/

How do you extract local variable information (address and type) from a Delphi program or the compiler-generated debug info?

Wouldn&#39;t the pointer returned by the following function be inaccessible?

    char *foo(int rc)
    {
        switch (rc)
        {
            case 1:

                return(&quot;one&quot;);

            case 2:

                return(&quot;two&quot;);

            default:

                return(&quot;whatever&quot;);
        }
    }

So the lifetime of a local variable in C/C++ is practically only within the function, right? Which means, after `char* foo(int)` terminates, the pointer it returns no longer means anything, right?

I&#39;m a bit confused about the lifetime of a local variable. What is a good clarification?


&quot;Life-time&quot; of a string literal in C

Based on [my reference][1], primitive types have default values and Objects are null. I tested a piece of code.

    public class Main {
        public static void main(String[] args) {
            int a;
            System.out.println(a);
        }
    }

The line `System.out.println(a);` will be an error pointing at the variable `a` that says `variable a might not have been initialized` whereas in the given reference, `integer` will have `0` as a default value. However, with the given code below, it will actually print `0`.

    public class Main {
        static int a;
        public static void main(String[] args) {
            System.out.println(a);
        }
    }

What could possibly go wrong with the first code? Do class variables behave different from local variables?

  [1]: http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html








Default values and initialization in Java

In `ArrayBlockingQueue`, all the methods that require the lock copy it to a local `final` variable before calling `lock()`.

    public boolean offer(E e) {
        if (e == null) throw new NullPointerException();
        final ReentrantLock lock = this.lock;
        lock.lock();
        try {
            if (count == items.length)
                return false;
            else {
                insert(e);
                return true;
            }
        } finally {
            lock.unlock();
        }
    }

Is there any reason to copy `this.lock` to a local variable `lock` when the field `this.lock` is `final`?

Additionally, it also uses a local copy of `E[]` before acting on it:

    private E extract() {
        final E[] items = this.items;
        E x = items[takeIndex];
        items[takeIndex] = null;
        takeIndex = inc(takeIndex);
        --count;
        notFull.signal();
        return x;
    }

Is there any reason for copying a final field to a local final variable?

In ArrayBlockingQueue, why copy final member field into local final variable?

How can I make a variable inside the try/except block public?


    import urllib.request

	try:
		url = &quot;http://www.google.com&quot;
		page = urllib.request.urlopen(url)
		text = page.read().decode(&#39;utf8&#39;)
	except (ValueError, RuntimeError, TypeError, NameError):
		print(&quot;Unable to process your request dude!!&quot;)

	print(text)


This code returns an error 

&gt; NameError: name &#39;text&#39; is not defined

How can I make the variable text available outside of the try/except block?

How to make a variable inside a try/except block public?

Take a look at below code:

    class Foo{
        public static int x = 1;
    }

    class Bar{    
        public static void main(String[] args) {
            Foo foo;
            System.out.println(foo.x); // Error: Variable &#39;foo&#39; might not have been initialized
        }
    }

As you see while trying to access static field `x` via an *uninitialized* local variable `Foo foo;` code `foo.x` generates compilation error: `Variable &#39;foo&#39; might not have been initialized`.

It could ***seem*** like this error makes sense, but only until we realize that to access a `static` member the JVM doesn&#39;t actually *use* the ***value*** of a variable, but only its ***type***.  

For instance I can initialize `foo` with value `null` and this will let us access `x` without any problems:

    Foo foo = null;
    System.out.println(foo.x); //compiles and at runtime prints 1!!! 

Such scenario works because compiler realizes that `x` is static and treats `foo.x` as if it was written like `Foo.x` (at least that is what I thought until now). 

So why compiler suddenly insists on `foo` having a value *which it will NOT use* at all?

----
&lt;sup&gt;Disclaimer: This is not code which would be used in real application, but interesting phenomenon which I couldn&#39;t find answer to on Stack Overflow, so I decided to ask about it.&lt;/sup&gt;


Why can&#39;t we access static content via uninitialized local variable?

Is there a defined order in which local variables are deallocated in C++ (11) ?
To be more concise: In which order will side effects of the destructors of two local variables in the same scope become visible?

e.g.:

    struct X{
      ~X(){/*do something*/}
    }

    int main(){
       X x1;
       X x2;
       return 0;
    }

Is `x1` or `x2` destroyed first when main returns or is the order undefined in C++11?

C++ local variable destruction order

I&#39;m new to Python, so this is probably a simple scoping question. The following code in a Python file (module) is confusing me slightly:

    if __name__ == &#39;__main__&#39;:
        x = 1
        
    print x

In other languages I&#39;ve worked in, this code would throw an exception, as the `x` variable is local to the `if` statement and should not exist outside of it. But this code executes, and prints 1. Can anyone explain this behavior? Are all variables created in a module global/available to the entire module?

What&#39;s the scope of a variable initialized in an if statement?

I am trying to access a local function variable outside the function in Python. So, for example,

    bye = &#39;&#39;
    def hi():
        global bye
        something
        something
        bye = 5
        sigh = 10

    hi()
    print bye

The above works fine as it should. Since I want to find out if I can access `bye` outside `hi()` without using `global bye`, I tried:

    def hi():
        something
        something
        bye = 5 
        sigh = 10
        return

    hi()
    x = hi()
    print x.bye 

The above gives `AttributeError: &#39;NoneType&#39; object has no attribute &#39;bye&#39;`.

Then, I tried:

    def hi():
        something
        something
        bye = 5
        sigh = 10
        return bye 
    hi()
    x = hi()
    print x.bye

This time it doesn&#39;t give even an error.

So, is there a way to access a local function variable (`bye`) outside its function (`hi()`) without using globals and without printing out variable `sigh` as well? (Question was edited to include `sigh` after @hcwhsa &#39;s comment below.






Access a function variable outside the function without using &quot;global&quot;

May I have any access to a local variable in a different function? If so, how?

    void replaceNumberAndPrint(int array[3]) {
        printf(&quot;%i\n&quot;, array[1]);
        printf(&quot;%i\n&quot;, array[1]);
    }

    int * getArray() {
        int myArray[3] = {4, 65, 23};
        return myArray;
    }

    int main() {
        replaceNumberAndPrint(getArray());
    }

The output of the piece of code above:

    65
    4202656

What am I doing wrong? What does the &quot;4202656&quot; mean?

Do I have to copy the whole array in the `replaceNumberAndPrint()` function to be able to access it more than the first time?


All Local Variables Solutions on Gang of Coders

Total of 16 Local Variables Solutions

Using locals() and format() method for strings: are there any caveats?

angular - using async pipe on observable<Object> and bind it to local variable in html

Undefine variable in Ruby

How to declare a variable in SQL Server and use it in the same Stored Procedure

Can a local variable's memory be accessed outside its scope?

Why do local variables require initialization, but fields do not?

How do you extract local variable information (address and type) from a Delphi program or the compiler-generated debug info?

"Life-time" of a string literal in C

Default values and initialization in Java

In ArrayBlockingQueue, why copy final member field into local final variable?

How to make a variable inside a try/except block public?

Why can't we access static content via uninitialized local variable?

C++ local variable destruction order

What's the scope of a variable initialized in an if statement?

Access a function variable outside the function without using "global"

How to access a local variable from a different function using pointers?