Question

我在C ++ 11中面临一个奇怪的编译错误。

我有一个模板化的类来定义枚举类：

template <typename Type>
class stats {
public:
  // ...
  enum class stat {
    AVERAGE = (1 << 0),
    STANDARD_DERIVATION = (1 << 1),
    // ...
  };
  // ...
};

我目前想在按位操作中使用此枚举。

例如，以下是该枚举的用法示例：

 template <typename Type>
 void
 stats<Type>::build(stat stats) {
     if (stats & stat::AVERAGE)
         this->build_average();

     if (stats & stat::STANDARD_DEVIATION)
         this->build_standard_deviation();

     if (stats & stat::PERCENTILES)
         this->build_percentiles();

     if (stats & stat::LIMITS)
         this->build_limits();
 }

我们可以像这样stats.build(stat::AVERAGE | stat::LIMITS)调用此函数。

为了在枚举上使用&或|运算符而不必每次都手动转换为int，我已经定义了运算符：

template<typename T>
using stat_t = typename eip::stats<T>::stat;

template <typename Type>
stat_t<Type>
operator|(const stat_t<Type>& lhs, const stat_t<Type>& rhs) {
  return static_cast<stat_t<Type>>(static_cast<int>(lhs) | static_cast<int>(rhs));
}

template <typename Type>
stat_t<Type>
operator&(const stat_t<Type>& lhs, const stat_t<Type>& rhs) {
    return static_cast<stat_t<Type>>(static_cast<int>(lhs) & static_cast<int>(rhs));
}

但是，如果我尝试编译，我会收到以下错误：

error: invalid operands to binary expression ('eip::stats<double>::stat' and 'eip::stats<double>::stat')
if (stats & stat::PERCENTILES)
    ~~~~~ ^ ~~~~~~~~~~~~~~~~~
candidate template ignored: couldn't infer template argument 'Type'
operator&(const stat_t<Type>& lhs, const stat_t<Type>& rhs) {
^

我不知道为什么忽略了我的超载。似乎编译器为lhs和rhs（eip::stats<double>::stat）得到了正确的类型，但它无法推断模板...

此外：

明确调用运算符（operator&<Type>(stats, stat::AVERAGE);）
我认为问题来自返回类型，但调用stat a = stats & stat::AVERAGE;不起作用（与之前的错误相同）。

有什么想法吗？

Answer 1

您的代码有两个问题。

这是一个不可导出的背景：

async function(){
  return string.replace(regex, async (match)=>{
    let data = await someFunction(match)
    console.log(data); //gives correct data
    return data;
  })
}

function replaceAsync(str, re, callback) {
    // http://es5.github.io/#x15.5.4.11
    str = String(str);
    var parts = [],
        i = 0;
    if (Object.prototype.toString.call(re) == "[object RegExp]") {
        if (re.global)
            re.lastIndex = i;
        var m;
        while (m = re.exec(str)) {
            var args = m.concat([m.index, m.input]);
            parts.push(str.slice(i, m.index), callback.apply(null, args));
            i = re.lastIndex;
            if (!re.global)
                break; // for non-global regexes only take the first match
            if (m[0].length == 0)
                re.lastIndex++;
        }
    } else {
        re = String(re);
        i = str.indexOf(re);
        parts.push(str.slice(0, i), callback.apply(null, [re, i, str]));
        i += re.length;
    }
    parts.push(str.slice(i));
    return Promise.all(parts).then(function(strings) {
        return strings.join("");
    });
}

这个想法和你写的一样：

C:\Glassfish\bin>asadmin start-domain
Waiting for domain1 to start ..........Error starting domain domain1.
The server exited prematurely with exit code 0.
Before it died, it produced the following output:

Launching GlassFish on Felix platform
Registered com.sun.enterprise.glassfish.bootstrap.osgi.EmbeddedOSGiGlassFishRunt
ime@810a64 in service registry.

    #!## LogManagerService.postConstruct : rootFolder=C:\Glassfish\glassfish
    #!## LogManagerService.postConstruct : templateDir=C:\Glassfish\glassfish\lib\te
    mplates
    #!## LogManagerService.postConstruct : src=C:\Glassfish\glassfish\lib\templates\
    logging.properties
    #!## LogManagerService.postConstruct : dest=C:\Glassfish\glassfish\domains\domain1\config\logging.properties
Completed shutdown of Log manager service
Completed shutdown of GlassFish runtime
Nov 10, 2015 1:58:57 PM com.sun.enterprise.glassfish.bootstrap.osgi.BundleProvis
ioner createBundleProvisioner
INFORMATION: Create bundle provisioner class = class com.sun.enterprise.glassfis
h.bootstrap.osgi.BundleProvisioner.
Nov 10, 2015 1:58:57 PM com.sun.enterprise.glassfish.bootstrap.osgi.BundleProvis
ioner$DefaultCustomizer getLocations
WARNUNG: Skipping entry  because it is not an absolute URI.
Nov 10, 2015 1:58:57 PM com.sun.enterprise.glassfish.bootstrap.osgi.BundleProvis
ioner$DefaultCustomizer getLocations
WARNUNG: Skipping entry  because it is not an absolute URI.
Nov 10, 2015 1:59:01 PM com.sun.enterprise.glassfish.bootstrap.osgi.BundleProvis
ioner startBundles
WARNUNG: Can not start bundle file:/C:/Glassfish/glassfish/modules/core.jar beca
use it is not contained in the list of installed bundles.
[#|2015-11-10T13:59:04.227+0100|INFO|glassfish 4.1|javax.enterprise.logging|_Thr
eadID=16;_ThreadName=RunLevelControllerThread-1447160343915;_TimeMillis=14471603
44227;_LevelValue=800;_MessageID=NCLS-LOGGING-00009;|
  Running GlassFish Version: GlassFish Server Open Source Edition 4.1.1  (build
 1)|#]

[#|2015-11-10T13:59:04.227+0100|INFO|glassfish 4.1|javax.enterprise.logging|_Thr
eadID=16;_ThreadName=RunLevelControllerThread-1447160343915;_TimeMillis=14471603
44227;_LevelValue=800;_MessageID=NCLS-LOGGING-00010;|
  Server log file is using Formatter class: com.sun.enterprise.server.logging.OD
LLogFormatter|#]

[#|2015-11-10T13:59:04.461+0100|INFO|glassfish 4.1|javax.enterprise.system.core.
security|_ThreadID=18;_ThreadName=RunLevelControllerThread-1447160343946;_TimeMi
llis=1447160344461;_LevelValue=800;_MessageID=NCLS-SECURITY-01115;|
  Realm [admin-realm] of classtype [com.sun.enterprise.security.auth.realm.file.
FileRealm] successfully created.|#]

[#|2015-11-10T13:59:04.477+0100|INFO|glassfish 4.1|javax.enterprise.system.core.
security|_ThreadID=18;_ThreadName=RunLevelControllerThread-1447160343946;_TimeMi
llis=1447160344477;_LevelValue=800;_MessageID=NCLS-SECURITY-01115;|
  Realm [file] of classtype [com.sun.enterprise.security.auth.realm.file.FileRea
lm] successfully created.|#]

[#|2015-11-10T13:59:04.477+0100|INFO|glassfish 4.1|javax.enterprise.system.core.
security|_ThreadID=18;_ThreadName=RunLevelControllerThread-1447160343946;_TimeMi
llis=1447160344477;_LevelValue=800;_MessageID=NCLS-SECURITY-01115;|
  Realm [certificate] of classtype [com.sun.enterprise.security.auth.realm.certi
ficate.CertificateRealm] successfully created.|#]

[#|2015-11-10T13:59:04.789+0100|INFO|glassfish 4.1|javax.enterprise.security.ser
vices|_ThreadID=17;_ThreadName=RunLevelControllerThread-1447160343946;_TimeMilli
s=1447160344789;_LevelValue=800;_MessageID=SEC-SVCS-00100;|
  Authorization Service has successfully initialized.|#]

[#|2015-11-10T13:59:04.820+0100|INFO|glassfish 4.1|org.hibernate.validator.inter
nal.util.Version|_ThreadID=15;_ThreadName=RunLevelControllerThread-1447160343915
;_TimeMillis=1447160344820;_LevelValue=800;|
  HV000001: Hibernate Validator 5.1.2.Final|#]

[#|2015-11-10T13:59:05.304+0100|INFO|glassfish 4.1|org.glassfish.ha.store.spi.Ba
ckingStoreFactoryRegistry|_ThreadID=16;_ThreadName=RunLevelControllerThread-1447
160343915;_TimeMillis=1447160345304;_LevelValue=800;|
  Registered org.glassfish.ha.store.adapter.cache.ShoalBackingStoreProxy for per
sistence-type = replicated in BackingStoreFactoryRegistry|#]

[#|2015-11-10T13:59:05.335+0100|WARNING|glassfish 4.1|org.glassfish.grizzly.conf
ig.Utils|_ThreadID=18;_ThreadName=RunLevelControllerThread-1447160343946;_TimeMi
llis=1447160345335;_LevelValue=900;|
  Instance could not be initialized. Class=interface org.glassfish.grizzly.http.
server.AddOn, name=http-listener-1, realClassName=org.glassfish.grizzly.http2.Ht
tp2AddOn|#]

[#|2015-11-10T13:59:05.428+0100|WARNING|glassfish 4.1|org.glassfish.grizzly.conf
ig.Utils|_ThreadID=18;_ThreadName=RunLevelControllerThread-1447160343946;_TimeMi
llis=1447160345428;_LevelValue=900;|
  Instance could not be initialized. Class=interface org.glassfish.grizzly.http.
server.AddOn, name=http-listener-2, realClassName=org.glassfish.grizzly.http2.Ht
tp2AddOn|#]

[#|2015-11-10T13:59:05.600+0100|INFO|glassfish 4.1|javax.enterprise.system.core|
_ThreadID=18;_ThreadName=RunLevelControllerThread-1447160343946;_TimeMillis=1447
160345600;_LevelValue=800;_MessageID=NCLS-CORE-00087;|
  Grizzly Framework 2.3.23 started in: 172ms - bound to [/0.0.0.0:8181]|#]

[#|2015-11-10T13:59:05.600+0100|WARNING|glassfish 4.1|org.glassfish.grizzly.conf
ig.Utils|_ThreadID=18;_ThreadName=RunLevelControllerThread-1447160343946;_TimeMi
llis=1447160345600;_LevelValue=900;|
  Instance could not be initialized. Class=interface org.glassfish.grizzly.http.
server.AddOn, name=admin-listener, realClassName=org.glassfish.grizzly.http2.Htt
p2AddOn|#]

[#|2015-11-10T13:59:05.616+0100|INFO|glassfish 4.1|javax.enterprise.system.core|
_ThreadID=18;_ThreadName=RunLevelControllerThread-1447160343946;_TimeMillis=1447
160345616;_LevelValue=800;_MessageID=NCLS-CORE-00087;|
  Grizzly Framework 2.3.23 started in: 16ms - bound to [/0.0.0.0:4848]|#]

[#|2015-11-10T13:59:05.662+0100|INFO|glassfish 4.1|javax.enterprise.system.core|
_ThreadID=16;_ThreadName=RunLevelControllerThread-1447160343915;_TimeMillis=1447
160345662;_LevelValue=800;_MessageID=NCLS-CORE-00087;|
  Grizzly Framework 2.3.23 started in: 0ms - bound to [/0.0.0.0:3700]|#]

[#|2015-11-10T13:59:05.662+0100|INFO|glassfish 4.1|javax.enterprise.system.core|
_ThreadID=1;_ThreadName=main;_TimeMillis=1447160345662;_LevelValue=800;_MessageI
D=NCLS-CORE-00017;|
  GlassFish Server Open Source Edition  4.1.1  (1) startup time : Felix (6.974ms
), startup services(1.762ms), total(8.736ms)|#]

[#|2015-11-10T13:59:05.662+0100|SEVERE|glassfish 4.1|javax.enterprise.system.cor
e|_ThreadID=1;_ThreadName=main;_TimeMillis=1447160345662;_LevelValue=1000;_Messa
geID=NCLS-CORE-00019;|
  Shutting down server due to startup exception
java.net.BindException: Address already in use: bind
        at sun.nio.ch.Net.bind0(Native Method)
        at sun.nio.ch.Net.bind(Unknown Source)
        at sun.nio.ch.Net.bind(Unknown Source)
        at sun.nio.ch.ServerSocketChannelImpl.bind(Unknown Source)
        at sun.nio.ch.ServerSocketAdaptor.bind(Unknown Source)
        at org.glassfish.grizzly.nio.transport.TCPNIOBindingHandler.bindToChanne
lAndAddress(TCPNIOBindingHandler.java:131)
        at org.glassfish.grizzly.nio.transport.TCPNIOBindingHandler.bind(TCPNIOB
indingHandler.java:88)
        at org.glassfish.grizzly.nio.transport.TCPNIOTransport.bind(TCPNIOTransp
ort.java:248)
        at org.glassfish.grizzly.nio.transport.TCPNIOTransport.bind(TCPNIOTransp
ort.java:237)
        at org.glassfish.grizzly.nio.transport.TCPNIOTransport.bind(TCPNIOTransp
ort.java:86)
        at org.glassfish.grizzly.config.GenericGrizzlyListener.start(GenericGriz
zlyListener.java:184)
        at com.sun.enterprise.v3.services.impl.GlassfishNetworkListener.start(Gl
assfishNetworkListener.java:109)
        at com.sun.enterprise.v3.services.impl.GrizzlyProxy.start0(GrizzlyProxy.
java:267)
        at com.sun.enterprise.v3.services.impl.GrizzlyProxy.start(GrizzlyProxy.j
ava:241)
        at com.sun.enterprise.v3.services.impl.GrizzlyService.createNetworkProxy
(GrizzlyService.java:567)
        at com.sun.enterprise.v3.services.impl.GrizzlyService.postConstruct(Griz
zlyService.java:490)
        at org.jvnet.hk2.internal.ClazzCreator.postConstructMe(ClazzCreator.java
:326)
        at org.jvnet.hk2.internal.ClazzCreator.create(ClazzCreator.java:374)
        at org.jvnet.hk2.internal.SystemDescriptor.create(SystemDescriptor.java:
471)
        at org.glassfish.hk2.runlevel.internal.AsyncRunLevelContext.findOrCreate
(AsyncRunLevelContext.java:228)
        at org.glassfish.hk2.runlevel.RunLevelContext.findOrCreate(RunLevelConte
xt.java:85)
        at org.jvnet.hk2.internal.Utilities.createService(Utilities.java:2072)
        at org.jvnet.hk2.internal.ServiceHandleImpl.getService(ServiceHandleImpl
.java:114)
        at org.jvnet.hk2.internal.ServiceHandleImpl.getService(ServiceHandleImpl
.java:88)
        at org.glassfish.hk2.runlevel.internal.CurrentTaskFuture$QueueRunner.one
Job(CurrentTaskFuture.java:1213)
        at org.glassfish.hk2.runlevel.internal.CurrentTaskFuture$QueueRunner.run
(CurrentTaskFuture.java:1144)
        at org.glassfish.hk2.runlevel.internal.CurrentTaskFuture$UpOneLevel.run(
CurrentTaskFuture.java:762)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
|#]

[#|2015-11-10T13:59:05.740+0100|INFO|glassfish 4.1|javax.enterprise.system.core|
_ThreadID=55;_ThreadName=Thread-11;_TimeMillis=1447160345740;_LevelValue=800;_Me
ssageID=NCLS-CORE-00092;|
  Server shutdown initiated|#]

[#|2015-11-10T13:59:05.740+0100|INFO|glassfish 4.1|javax.enterprise.bootstrap|_T
hreadID=1;_ThreadName=main;_TimeMillis=1447160345740;_LevelValue=800;_MessageID=
NCLS-BOOTSTRAP-00027;|
  Registered com.sun.enterprise.glassfish.bootstrap.osgi.EmbeddedOSGiGlassFishIm
pl@1aa7d76 as OSGi service registration: org.apache.felix.framework.ServiceRegis
trationImpl@1a6a933.|#]

[#|2015-11-10T13:59:06.754+0100|INFO|glassfish 4.1|javax.enterprise.bootstrap|_T
hreadID=55;_ThreadName=Thread-11;_TimeMillis=1447160346754;_LevelValue=800;_Mess
ageID=NCLS-BOOTSTRAP-00028;|
  Unregistered com.sun.enterprise.glassfish.bootstrap.osgi.EmbeddedOSGiGlassFish
Impl@1aa7d76 from service registry.|#]

[#|2015-11-10T13:59:06.754+0100|INFO|glassfish 4.1||_ThreadID=55;_ThreadName=Thr
ead-8;_TimeMillis=1447160346754;_LevelValue=800;|
  FileMonitoring shutdown|#]

[#|2015-11-10T13:59:06.942+0100|INFO|glassfish 4.1|javax.enterprise.system.core|
_ThreadID=55;_ThreadName=Thread-11;_TimeMillis=1447160346942;_LevelValue=800;_Me
ssageID=NCLS-CORE-00013;|
  Shutdown procedure finished|#]

Java HotSpot(TM) Client VM warning: ignoring option MaxPermSize=192m; support wa
s removed in 8.0

Command start-domain failed.

C:\Glassfish\bin>

编译器无法确定template <typename Type> stat_t<Type> operator&(const stat_t<Type>& lhs, const stat_t<Type>& rhs) { ... }可能存在的内容，除非你也说出来。因此，您必须在我们实际上不需要进行演绎的地方定义您的template <typename T> void foo(typename cls<T>::type ) { ... }：将其作为班级中的朋友操作员：

一旦我们解决了这个问题，我们就会遇到另一个问题，即operator&无法在上下文中转换为friend stat operator&(const stat& lhs, const stat& rhs) { ... }所以这个表达式：
```
stat
```
不会编译。为此，您可能希望让bool返回if (stats & stat::AVERAGE)或operator&，或使用this answer的想法，添加int和使用它两次。

C ++二进制表达式的操作数无效

1 个答案: