参数是如何传递给这个匿名函数的？

Question

我不太理解下面代码中下面一行的约定

request.transformRequest = internal.transformRequest;

这实际上是调用internal.transformRequest函数，还是只是将函数设置为request对象中同名的方法？我认为它是在调用函数，因为代码中的任何地方都不会调用transformRequest，但是在这种情况下，data和getHeaders的参数是如何传递的呢？

internal.transformResourceUrl = function (url) {
        if (url.substr(-1) === '/')
            url = url.substr(0, url.length - 1);
        return url + '.json';
    };

    internal.transformRequest = function (data, getHeaders) {
        // If this is not an object, defer to native stringification.
        if (!angular.isObject(data)) {
            return (data === null) ? '' : data.toString();
        }

        var buffer = [];
        // Serialize each key in the object.
        for (var name in data) {
            if (!data.hasOwnProperty(name)) continue;
            var value = data[name];
            buffer.push(
                encodeURIComponent(name) +
                '=' +
                encodeURIComponent((value === null) ? '' : value )
            );
        }

        // Serialize the buffer and clean it up for transportation.
        var source = buffer
            .join('&')
            .replace(/%20/g, '+')
        ;

        return source;
    };

    internal.generateRequest = function (method, resource, data, account) {
        method = method.toUpperCase();

        if (!angular.isString(account) || account.length < 1)
            account = '_default';

        resource = 'Accounts/' +
            accounts[account] + '/' +
            internal.transformResourceUrl(resource);

        var request = {
            method: method,
            url: apiEndpoint + resource,
            headers: {
                'Authorization': 'Basic ' + credentialsB64
            }
        };

        if (method === 'POST' || method === 'PUT') {
            if (data) request.data = data;
            request.transformRequest = internal.transformRequest;
            request.headers['content-type'] = 'application/x-www-form-urlencoded; charset=utf-8';
        } else if (data) {
            request.params = data;
        }
        return $http(request);
    };

Answer 1

“这实际上是调用internal.transformRequest函数，还是只设置等于方法的函数？”

“我认为它是在调用函数，因为代码中的任何地方都不会调用transformRequest”

internal.transformRequest 方法如何被称为

第7行：transformRequest：方法(函数)添加到internal :object中

internal.transformRequest = function (data, getHeaders) {

第54行:将transformRequest属性request :object赋值给上述方法

request.transformRequest = internal.transformRequest;

第59行：$http() :function是用request :object调用的，该对象现在具有指向internal.transformRequest的transformRequest：方法

return $http(request);