def homebrew_formula(name, src, binary, out, visibility = None):
    """
    Generates a Homebrew formula with the SHA256 of the binary injected.
    
    Args:
        name: The name of the rule.
        src: The template file (.rb.tpl).
        binary: The binary target to hash.
        out: The output filename (.rb).
        visibility: Visibility of the rule.
    """
    native.genrule(
        name = name,
        srcs = [src, binary],
        outs = [out],
        cmd = """
            TEMPLATE=$(location %s)
            BINARY=$(location %s)
            
            # Calculate SHA256
            if command -v sha256sum >/dev/null 2>&1; then
                HASH=$$(sha256sum $$BINARY | cut -d' ' -f1)
            else
                HASH=$$(shasum -a 256 $$BINARY | cut -d' ' -f1)
            fi
            
            # Substitute into template
            sed "s/{SHA256}/$$HASH/g" $$TEMPLATE > $@
        """ % (src, binary),
        visibility = visibility,
    )