¿Cuándo utilizar los valores locales de referencia y los valores de retorno de referencia?

When to use Ref locals and ref return values?

A reference return value allows a method to return a reference to a variable, rather than a value, back to a caller. The caller can then choose to treat the returned variable as if it were returned by value or by reference. The caller can create a new variable that is itself a reference to the returned value, called a ref local.

An asynchronous method may return before it has finished execution, while its return value is still unknown. A method that returns a reference return value must satisfy the following two conditions: The method signature includes the ref keyword in front of the return type.

It follows that methods returning by reference can’t have the return type void. There are some restrictions on the expression that a method can return as a reference return value. Restrictions include: The return value must have a lifetime that extends beyond the execution of the method.

A method with a ref return can return an alias to a variable whose value is currently the null (uninstantiated) value or a nullable type for a value type. The return value cannot be a constant, an enumeration member, the by-value return value from a property, or a method of a class or struct.

TypeError. What went wrong? It attempted to call a value from a function, but the value is not actually a function. Some code expects you to provide a function, but that didn’t happen. Maybe there is a typo in the function name? Maybe the object you are calling the method on does not have this function?

Attempting to return a local variable generates compiler error CS8168, “Cannot return local ‘obj’ by reference because it is not a ref local.” The return value cannot be the literal null. Returning null generates compiler error CS8156, “An expression cannot be used in this context because it may not be returned by reference.”

Ref local variables must still be initialized when they are declared. The following example defines a NumberStore class that stores an array of integer values. The FindNumber method returns by reference the first number that is greater than or equal to the number passed as an argument.

Variables allow you to store and reuse values in your requests and scripts. By storing a value in a variable, you can reference it throughout your collections, environments, and requests—and if you need to update the value, you only have to change it in one place.

Failure to include both ref keywords in the variable declaration and assignment in both examples results in compiler error CS8172, “Cannot initialize a by-reference variable with a value.” Prior to C# 7.3, ref local variables couldn’t be reassigned to refer to different storage after being initialized. That restriction has been removed.

Any changes made to its value by the called method are observed by the caller. A reference return value means that a method returns a reference (or an alias) to some variable. That variable’s scope must include the method. That variable’s lifetime must extend beyond the return of the method.

For more information, see Compiler Options. C# programmers should know that ref in C# is not the same thing as ref in F#. The equivalent constructs in F# are byrefs, which are a different concept from reference cells. Values marked as mutable may be automatically promoted to ‘a ref if captured by a closure; see Values.

Return by reference is very different from Call by reference. Functions behaves a very important role when variable or pointers are returned as reference. See this function signature of Return by Reference Below: and parameters are the passed arguments to it. Below is the code to illustrate the Return by reference:

Various model approaches have been developed to describe the two-phase flow and interphase interactions. Nevertheless, real flow behaviour in structured packings has not yet been completely captured because of the flow complexity and its limited accessibility.

The latest version of the equation is in Reference 108: C o = constant, value of 3.08 in. Equation 14-94 recommended for all structured packings similar to such types as Flexipac 2® and Gempak 2®. Note: Reference 108 provides values for other structured packing sizes and styles and wire gauze.