12.5.md

Since we do not make the constructor explicit, the pros are

• we can use = { /* ... */ } to initialize a StrBlob object,
• we can use assignment to assign an initializer list to a StrBlob object,
• we can pass an initializer list to functions who need a StrBlob parameter.

The cons are

• we may overlook the implicit conversion made by compiler sometime, which may be bug prone.