使用申请或致电＆＃34; old＆＃34;上下文

Question

B = function(fn) {

    var ex_array = ['a', 'b'];

    this.b_fn = function () {
        fn.apply(what_should_be_there, ex_array);
    }

}

A = function() {

    this.a_fn = function (a, b) {
         //do sth
    }

    var b = new B(fn); 

}

我想要做的只是将apply与对象fn中的函数b一起使用，但使用＆＃34; old＆＃34;上下文，我的意思是在这种情况下使用类A

的对象的上下文

Answer 1

修改

如果您想将public class FragmentVictoriaLine extends android.support.v4.app.Fragment implements { private class Victoria { private CharSequence station; private CharSequence zone; private Class<? extends Activity> activityClass; private Class<? extends android.support.v4.app.Fragment> fragmentClass; public Victoria(int stationResId, int zoneResId, Class<? extends Activity> activityClass, Class<? extends android.support.v4.app.Fragment> fragmentClass) { this.fragmentClass = fragmentClass; this.activityClass = activityClass; this.station = getResources().getString(stationResId); this.zone = getResources().getString(zoneResId); } @Override public String toString() { return station.toString(); } public String getzone(){ return zone.toString(); } } private static Victoria[] mVictoria; /** * Whether or not the activity is in two-pane mode, i.e. running on a tablet * device. */ public boolean mTwoPane; public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){ View v = inflater.inflate(R.layout.fragment_victoria_line, container, false); if (getActivity().findViewById(R.id.detail_container) != null) { mTwoPane = true; }else{ mTwoPane = false; } // Instantiate the list of stations. mVictoria = new Victoria[]{ new Victoria(R.string.bank, R.string.zone_1, WCBankActivity.class, FragmentWCBank.class), new Victoria(R.string.wat, R.string.zone_1, WCWATActivity.class, FragmentWCWAT.class) }; final ListView listView = (ListView)v.findViewById(R.id.list_victoria); listView.setAdapter(new MyAdapter(getActivity(), mVictoria)); listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE); listView.setTextFilterEnabled(true); }); return v; } public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); setHasOptionsMenu(true); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu items for use in the action bar MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.menu_victoria_line, menu); // Associate searchable configuration with the SearchView SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE); SearchView searchView = (SearchView) menu.findItem(R.id.action_search).getActionView(); searchView.setSearchableInfo(searchManager.getSearchableInfo(getComponentName())); searchView.setIconifiedByDefault(false); android.support.v7.widget.SearchView.OnQueryTextListener textChangeListener = new android.support.v7.widget.SearchView.OnQueryTextListener() { @Override public boolean onQueryTextChange(String newText) { // this is your adapter that will be filtered myAdapter.getFilter().filter(newText); return true; } @Override public boolean onQueryTextSubmit(String query) { // this is your adapter that will be filtered myAdapter.getFilter().filter(query); return true; } }; searchView.setOnQueryTextListener(textChangeListener); return super.onCreateOptionsMenu(menu); } static class MyAdapter extends BaseAdapter { static class ViewHolder { TextView station; TextView zone; } LayoutInflater inflater; Victoria[] mVictoria; public MyAdapter(Context contexts, Victoria[] samples) { this.mVictoria = samples; inflater = LayoutInflater.from(contexts); } @Override public int getCount() { return mVictoria.length; } @Override public Object getItem(int position) { return mVictoria[position]; } @Override public long getItemId(int position) { return 0; } @Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolder viewHolder; if (convertView == null) { convertView = inflater.inflate(R.layout.list_item_dualline, null); viewHolder = new ViewHolder(); viewHolder.station = (TextView) convertView.findViewById(R.id.list_item_station); viewHolder.zone = (TextView) convertView.findViewById(R.id.list_item_zone); convertView.setTag(viewHolder); } else { viewHolder = (ViewHolder) convertView.getTag(); } viewHolder.station.setText(mVictoria[position].station); viewHolder.zone.setText(mVictoria[position].getzone()); return convertView; } } } 用作参数数组，以便ex_array遍历它们，请执行此操作（jsfiddle）：

apply

上一个回答

请参阅此working demo on jsfiddle：

B = function(fn) {

    var ex_array = ['a', 'b'];

    this.b_fn = function() {
      return fn.apply(null, ex_array);  
    };

}

A = function() {

    this.a_fn = function (a, b) {
         console.log(this, a, b);
    }

    var b = new B(this.a_fn.bind(this)); 

    b.b_fn(); // => A {}, "a", "b"

}

new A();

基本上，您需要做的就是将B = function(fn) { var ex_array = ['a', 'b']; this.b_fn = fn.bind(null, ex_array); } A = function() { this.a_fn = function (a, b) { console.log(this, a); } var b = new B(this.a_fn.bind(this)); b.b_fn(); // => A {}, ['a', 'b']; } new A(); 与其当前上下文绑定。诀窍在于this.a_fn时使用.bind(null, /* args */)，因此它会保留原始this.b_fn上下文，但允许您传入另一个参数（在本例中为A）。

Answer 2

这是一个ic[j] = Form1.dt.Rows[i][5].ToString(); 未预先绑定到参数数组的解决方案。我添加了一些日志记录作为演示：

a_fn