How Does the Unary Plus Operator ( ) Enable Redefinition of a Non-Capturing Lambda Expression ( []{}) in C 11?

A Positive Lambda: []{} - Revealing the Enchantment Behind

In the realm of programming, unusual observations often spark curiosity and unveil hidden truths. In the case of the lambda expression []{}, the addition of a simple unary operator has bewildered developers. This article delves into the magic behind this enigmatic code snippet.

In the original dilemma, attempts to redefine a lambda in C 11 resulted in compilation errors. However, Johannes Schaub's astute observation introduced a captivating twist: adding a before the first lambda seemingly resolved the issue. This paradoxical behavior begs the question: how does this altered code manage to function?

To unravel this sorcery, we need to understand the underlying mechanics. The operator in this instance triggers a conversion of the lambda into a plain old function pointer. This conversion is enabled by the absence of captures in the lambda, fulfilling the requirements of §5.1.2.

According to §5.1.2, a non-capturing lambda has a public conversion function that allows for conversion to a function pointer. Crucially, this function pointer shares the same parameter and return types as the lambda.

With this knowledge, we can understand the role of the operator. It initiates a search for suitable overloads, and in the case of the lambda closure object, it identifies the conversion to the function pointer. This conversion, along with the subsequent assignment in the second line, ultimately enables the redefinition of the lambda.

In conclusion, the operator bestowed upon the lambda a hidden power of transformation, enabling its conversion into a function pointer. This conversion aligns with the standard-defined behavior, allowing for the successful redefinition of the lambda. This arcane knowledge empowers developers with a weapon against compiling demons, shedding light on the once mysterious []{} lambda.

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