How to use True method of is Package

1// Copyright 2016 The Go Authors. All rights reserved.2// Use of this source code is governed by a BSD-style3// license that can be found in the LICENSE file.4// Package httplex contains rules around lexical matters of various5// HTTP-related specifications.6//7// This package is shared by the standard library (which vendors it)8// and x/net/http2. It comes with no API stability promise.9package httplex10import (11	"net"12	"strings"13	"unicode/utf8"14	"golang.org/x/net/idna"15)16var isTokenTable = [127]bool{17	'!':  true,18	'#':  true,19	'$':  true,20	'%':  true,21	'&':  true,22	'\'': true,23	'*':  true,24	'+':  true,25	'-':  true,26	'.':  true,27	'0':  true,28	'1':  true,29	'2':  true,30	'3':  true,31	'4':  true,32	'5':  true,33	'6':  true,34	'7':  true,35	'8':  true,36	'9':  true,37	'A':  true,38	'B':  true,39	'C':  true,40	'D':  true,41	'E':  true,42	'F':  true,43	'G':  true,44	'H':  true,45	'I':  true,46	'J':  true,47	'K':  true,48	'L':  true,49	'M':  true,50	'N':  true,51	'O':  true,52	'P':  true,53	'Q':  true,54	'R':  true,55	'S':  true,56	'T':  true,57	'U':  true,58	'W':  true,59	'V':  true,60	'X':  true,61	'Y':  true,62	'Z':  true,63	'^':  true,64	'_':  true,65	'`':  true,66	'a':  true,67	'b':  true,68	'c':  true,69	'd':  true,70	'e':  true,71	'f':  true,72	'g':  true,73	'h':  true,74	'i':  true,75	'j':  true,76	'k':  true,77	'l':  true,78	'm':  true,79	'n':  true,80	'o':  true,81	'p':  true,82	'q':  true,83	'r':  true,84	's':  true,85	't':  true,86	'u':  true,87	'v':  true,88	'w':  true,89	'x':  true,90	'y':  true,91	'z':  true,92	'|':  true,93	'~':  true,94}95func IsTokenRune(r rune) bool {96	i := int(r)97	return i < len(isTokenTable) && isTokenTable[i]98}99func isNotToken(r rune) bool {100	return !IsTokenRune(r)101}102// HeaderValuesContainsToken reports whether any string in values103// contains the provided token, ASCII case-insensitively.104func HeaderValuesContainsToken(values []string, token string) bool {105	for _, v := range values {106		if headerValueContainsToken(v, token) {107			return true108		}109	}110	return false111}112// isOWS reports whether b is an optional whitespace byte, as defined113// by RFC 7230 section 3.2.3.114func isOWS(b byte) bool { return b == ' ' || b == '\t' }115// trimOWS returns x with all optional whitespace removes from the116// beginning and end.117func trimOWS(x string) string {118	// TODO: consider using strings.Trim(x, " \t") instead,119	// if and when it's fast enough. See issue 10292.120	// But this ASCII-only code will probably always beat UTF-8121	// aware code.122	for len(x) > 0 && isOWS(x[0]) {123		x = x[1:]124	}125	for len(x) > 0 && isOWS(x[len(x)-1]) {126		x = x[:len(x)-1]127	}128	return x129}130// headerValueContainsToken reports whether v (assumed to be a131// 0#element, in the ABNF extension described in RFC 7230 section 7)132// contains token amongst its comma-separated tokens, ASCII133// case-insensitively.134func headerValueContainsToken(v string, token string) bool {135	v = trimOWS(v)136	if comma := strings.IndexByte(v, ','); comma != -1 {137		return tokenEqual(trimOWS(v[:comma]), token) || headerValueContainsToken(v[comma+1:], token)138	}139	return tokenEqual(v, token)140}141// lowerASCII returns the ASCII lowercase version of b.142func lowerASCII(b byte) byte {143	if 'A' <= b && b <= 'Z' {144		return b + ('a' - 'A')145	}146	return b147}148// tokenEqual reports whether t1 and t2 are equal, ASCII case-insensitively.149func tokenEqual(t1, t2 string) bool {150	if len(t1) != len(t2) {151		return false152	}153	for i, b := range t1 {154		if b >= utf8.RuneSelf {155			// No UTF-8 or non-ASCII allowed in tokens.156			return false157		}158		if lowerASCII(byte(b)) != lowerASCII(t2[i]) {159			return false160		}161	}162	return true163}164// isLWS reports whether b is linear white space, according165// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2166//      LWS            = [CRLF] 1*( SP | HT )167func isLWS(b byte) bool { return b == ' ' || b == '\t' }168// isCTL reports whether b is a control byte, according169// to http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2170//      CTL            = <any US-ASCII control character171//                       (octets 0 - 31) and DEL (127)>172func isCTL(b byte) bool {173	const del = 0x7f // a CTL174	return b < ' ' || b == del175}176// ValidHeaderFieldName reports whether v is a valid HTTP/1.x header name.177// HTTP/2 imposes the additional restriction that uppercase ASCII178// letters are not allowed.179//180//  RFC 7230 says:181//   header-field   = field-name ":" OWS field-value OWS182//   field-name     = token183//   token          = 1*tchar184//   tchar = "!" / "#" / "$" / "%" / "&" / "'" / "*" / "+" / "-" / "." /185//           "^" / "_" / "`" / "|" / "~" / DIGIT / ALPHA186func ValidHeaderFieldName(v string) bool {187	if len(v) == 0 {188		return false189	}190	for _, r := range v {191		if !IsTokenRune(r) {192			return false193		}194	}195	return true196}197// ValidHostHeader reports whether h is a valid host header.198func ValidHostHeader(h string) bool {199	// The latest spec is actually this:200	//201	// http://tools.ietf.org/html/rfc7230#section-5.4202	//     Host = uri-host [ ":" port ]203	//204	// Where uri-host is:205	//     http://tools.ietf.org/html/rfc3986#section-3.2.2206	//207	// But we're going to be much more lenient for now and just208	// search for any byte that's not a valid byte in any of those209	// expressions.210	for i := 0; i < len(h); i++ {211		if !validHostByte[h[i]] {212			return false213		}214	}215	return true216}217// See the validHostHeader comment.218var validHostByte = [256]bool{219	'0': true, '1': true, '2': true, '3': true, '4': true, '5': true, '6': true, '7': true,220	'8': true, '9': true,221	'a': true, 'b': true, 'c': true, 'd': true, 'e': true, 'f': true, 'g': true, 'h': true,222	'i': true, 'j': true, 'k': true, 'l': true, 'm': true, 'n': true, 'o': true, 'p': true,223	'q': true, 'r': true, 's': true, 't': true, 'u': true, 'v': true, 'w': true, 'x': true,224	'y': true, 'z': true,225	'A': true, 'B': true, 'C': true, 'D': true, 'E': true, 'F': true, 'G': true, 'H': true,226	'I': true, 'J': true, 'K': true, 'L': true, 'M': true, 'N': true, 'O': true, 'P': true,227	'Q': true, 'R': true, 'S': true, 'T': true, 'U': true, 'V': true, 'W': true, 'X': true,228	'Y': true, 'Z': true,229	'!':  true, // sub-delims230	'$':  true, // sub-delims231	'%':  true, // pct-encoded (and used in IPv6 zones)232	'&':  true, // sub-delims233	'(':  true, // sub-delims234	')':  true, // sub-delims235	'*':  true, // sub-delims236	'+':  true, // sub-delims237	',':  true, // sub-delims238	'-':  true, // unreserved239	'.':  true, // unreserved240	':':  true, // IPv6address + Host expression's optional port241	';':  true, // sub-delims242	'=':  true, // sub-delims243	'[':  true,244	'\'': true, // sub-delims245	']':  true,246	'_':  true, // unreserved247	'~':  true, // unreserved248}249// ValidHeaderFieldValue reports whether v is a valid "field-value" according to250// http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2 :251//252//        message-header = field-name ":" [ field-value ]253//        field-value    = *( field-content | LWS )254//        field-content  = <the OCTETs making up the field-value255//                         and consisting of either *TEXT or combinations256//                         of token, separators, and quoted-string>257//258// http://www.w3.org/Protocols/rfc2616/rfc2616-sec2.html#sec2.2 :259//260//        TEXT           = <any OCTET except CTLs,261//                          but including LWS>262//        LWS            = [CRLF] 1*( SP | HT )263//        CTL            = <any US-ASCII control character264//                         (octets 0 - 31) and DEL (127)>265//266// RFC 7230 says:267//  field-value    = *( field-content / obs-fold )268//  obj-fold       =  N/A to http2, and deprecated269//  field-content  = field-vchar [ 1*( SP / HTAB ) field-vchar ]270//  field-vchar    = VCHAR / obs-text271//  obs-text       = %x80-FF272//  VCHAR          = "any visible [USASCII] character"273//274// http2 further says: "Similarly, HTTP/2 allows header field values275// that are not valid. While most of the values that can be encoded276// will not alter header field parsing, carriage return (CR, ASCII277// 0xd), line feed (LF, ASCII 0xa), and the zero character (NUL, ASCII278// 0x0) might be exploited by an attacker if they are translated279// verbatim. Any request or response that contains a character not280// permitted in a header field value MUST be treated as malformed281// (Section 8.1.2.6). Valid characters are defined by the282// field-content ABNF rule in Section 3.2 of [RFC7230]."283//284// This function does not (yet?) properly handle the rejection of285// strings that begin or end with SP or HTAB.286func ValidHeaderFieldValue(v string) bool {287	for i := 0; i < len(v); i++ {288		b := v[i]289		if isCTL(b) && !isLWS(b) {290			return false291		}292	}293	return true294}295func isASCII(s string) bool {296	for i := 0; i < len(s); i++ {297		if s[i] >= utf8.RuneSelf {298			return false299		}300	}301	return true302}303// PunycodeHostPort returns the IDNA Punycode version304// of the provided "host" or "host:port" string.305func PunycodeHostPort(v string) (string, error) {306	if isASCII(v) {307		return v, nil308	}309	host, port, err := net.SplitHostPort(v)310	if err != nil {311		// The input 'v' argument was just a "host" argument,312		// without a port. This error should not be returned313		// to the caller.314		host = v315		port = ""316	}317	host, err = idna.ToASCII(host)318	if err != nil {319		// Non-UTF-8? Not representable in Punycode, in any320		// case.321		return "", err322	}323	if port == "" {324		return host, nil325	}326	return net.JoinHostPort(host, port), nil327}...

1import "fmt"2func main() {3    var i interface{}4    describe(i)5    describe(i)6    describe(i)7}8func describe(i interface{}) {9    fmt.Printf("(%v, %T)10}11import "fmt"12func main() {13    var i interface{}14    describe(i)15    describe(i)16    describe(i)17}18func describe(i interface{}) {19    fmt.Printf("(%v, %T)20}21import "fmt"22func main() {23    var i interface{}24    describe(i)25    describe(i)26    describe(i)27}28func describe(i interface{}) {29    fmt.Printf("(%v, %T)30}31import "fmt"32func main() {33    var i interface{}34    describe(i)35    describe(i)36    describe(i)37}38func describe(i interface{}) {39    fmt.Printf("(%v, %T)40}41import "fmt"42func main() {43    var i interface{}44    describe(i)45    describe(i)46    describe(i)47}48func describe(i interface{}) {49    fmt.Printf("(%v, %T)50}51import "fmt"

1import (2func main() {3    fmt.Println(is.True())4}5import (6func main() {7    fmt.Println(is.False())8}9import (10func main() {11    fmt.Println(is.True())12}13So the question is, how do I cache the package so that it is not being re-imported?14router.HandleFunc("/api/v1/notes/{id}", controllers.GetNote).Methods("GET")15func GetNote(w http.ResponseWriter, r *http.Request) {16    vars := mux.Vars(r)17    fmt.Fprintf(w, "Note: %s", id)18}19github.com/gorilla/mux.(*Router).Vars(0x0, 0xc0000a8000, 0xc0000a8000)

1import (2func main() {3	fmt.Println(myPackage.True)4}5import (6func main() {7	fmt.Println(myPackage.True)8}9import (10func main() {11	fmt.Println(myPackage.True)12}13import (14func main() {15	fmt.Println(myPackage.True)16}17import (18func main() {19	fmt.Println(myPackage.True)20}21import (22func main() {23	fmt.Println(myPackage.True)24}25import (26func main() {27	fmt.Println(myPackage.True)28}29import (30func main() {31	fmt.Println(myPackage.True)32}33import (34func main() {35	fmt.Println(myPackage.True)36}37import (38func main() {39	fmt.Println(myPackage.True)40}41import (42func main() {43	fmt.Println(myPackage.True)44}45import (46func main() {47	fmt.Println(myPackage.True)48}

1import (2func main() {3	fmt.Println("Hello, playground")4	myclass.True()5}6import "fmt"7func True() {8	fmt.Println("True")9}10	/usr/local/go/src/pkg/myclass (from $GOROOT)11	/Users/username/gopath/src/pkg/myclass (from $GOPATH)12	/usr/local/go/src/pkg/myclass (from $GOROOT)13	/Users/username/gopath/src/pkg/myclass (from $GOPATH)14	/usr/local/go/src/pkg/github.com/username/myclass (from $GOROOT)15	/Users/username/gopath/src/pkg/github.com/username/myclass (from $GOPATH)

1import (2func main() {3	fmt.Println("Hello World")4	fmt.Println(is.True())5}6func True() bool {7}81: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, not stripped

1import (2func main() {3    fmt.Println("is true:", is.True(true))4    fmt.Println("is false:", is.False(true))5}6import (7func main() {8    fmt.Println("is true:", is.True(true))9    fmt.Println("is false:", is.False(true))10}11import (12func main() {13    fmt.Println("is true:", is.True(true))14    fmt.Println("is false:", is.False(true))15}16import (17func main() {18    fmt.Println("is true:", is.True(true))19    fmt.Println("is false:", is.False(true))20}21import (22func main() {23    fmt.Println("is true:", is.True(true))24    fmt.Println("is false:", is.False(true))25}26import (27func main() {28    fmt.Println("is true:", is.True(true))29    fmt.Println("is false:", is.False(true))30}31import

1import "fmt"2func main() {3fmt.Println(a)4}5import "fmt"6func main() {7fmt.Println(a)8}9import "fmt"10func main() {11fmt.Println(a)12}13import "fmt"14func main() {15var b float64 = float64(a)16fmt.Println(b)17}18import "fmt"19func main() {20fmt.Println(a)21}22import "fmt"23func main() {24fmt.Println(a)25}26import "fmt"27func main() {28var a interface{} = 65