In Twig, check if a specific key of an array exists
Twig example: {% if array.key is defined %} // do something {% else %} // do something else {% endif %}
conditional
Conditional build based on environment using Webpack
You can use the define plugin. I use it by doing something as simple as this in your webpack build file where env is the path to a file that exports an object of settings: // Webpack build config plugins: [ new webpack.DefinePlugin({ ENV: require(path.join(__dirname, ‘./path-to-env-files/’, env)) }) ] // Settings file located at `path-to-env-files/dev.js` … Read more
MySQL Conditional Insert
If your DBMS does not impose limitations on which table you select from when you execute an insert, try: INSERT INTO x_table(instance, user, item) SELECT 919191, 123, 456 FROM dual WHERE NOT EXISTS (SELECT * FROM x_table WHERE user = 123 AND item = 456) In this, dual is a table with one row only … Read more
How does “do something OR DIE()” work in PHP?
If the first statement returns true, then the entire statement must be true therefore the second part is never executed. For example: $x = 5; true or $x++; echo $x; // 5 false or $x++; echo $x; // 6 Therefore, if your query is unsuccessful, it will evaluate the die() statement and end the script.
#ifdef #ifndef in Java
private static final boolean enableFast = false; // … if (enableFast) { // This is removed at compile time } Conditionals like that shown above are evaluated at compile time. If instead you use this private static final boolean enableFast = “true”.equals(System.getProperty(“fast”)); Then any conditions dependent on enableFast will be evaluated by the JIT compiler. … Read more
How to compare strings in C conditional preprocessor-directives
I don’t think there is a way to do variable length string comparisons completely in preprocessor directives. You could perhaps do the following though: #define USER_JACK 1 #define USER_QUEEN 2 #define USER USER_JACK #if USER == USER_JACK #define USER_VS USER_QUEEN #elif USER == USER_QUEEN #define USER_VS USER_JACK #endif Or you could refactor the code a … Read more
VBA – how to conditionally skip a for loop iteration
VBA does not have a Continue or any other equivalent keyword to immediately jump to the next loop iteration. I would suggest a judicious use of Goto as a workaround, especially if this is just a contrived example and your real code is more complicated: For i = LBound(Schedule, 1) To UBound(Schedule, 1) If (Schedule(i, … Read more
Syntax for if/else condition in SCSS mixin
You can assign default parameter values inline when you first create the mixin: @mixin clearfix($width: ‘auto’) { @if $width == ‘auto’ { // if width is not passed, or empty do this } @else { display: inline-block; width: $width; } }
IF… OR IF… in a windows batch file
The zmbq solution is good, but cannot be used in all situations, such as inside a block of code like a FOR DO(…) loop. An alternative is to use an indicator variable. Initialize it to be undefined, and then define it only if any one of the OR conditions is true. Then use IF DEFINED … Read more
Conditional with statement in Python
Python 3.3 and above Python 3.3 introduced contextlib.ExitStack for just this kind of situation. It gives you a “stack”, to which you add context managers as necessary. In your case, you would do this: from contextlib import ExitStack with ExitStack() as stack: if needs_with(): gs = stack.enter_context(get_stuff()) # do nearly the same large block of … Read more