我目前正在為libfreefare編寫Go 包裝器。libfreefare 的 API 包含以下函數(shù)：struct mifare_desfire_file_settings { uint8_t file_type; uint8_t communication_settings; uint16_t access_rights; union { struct { uint32_t file_size; } standard_file; struct { int32_t lower_limit; int32_t upper_limit; int32_t limited_credit_value; uint8_t limited_credit_enabled; } value_file; struct { uint32_t record_size; uint32_t max_number_of_records; uint32_t current_number_of_records; } linear_record_file; } settings;};int mifare_desfire_get_file_settings (MifareTag tag, uint8_t file_no, struct mifare_desfire_file_settings *settings);包裝這樣一個功能的理想解決方案是什么？如果struct mifare_desfire_file_settings不包含任何聯(lián)合，我的包裝器可能看起來像這樣：type DESFireFileSettings struct { // all fields exported, no methods}func (t DESFireTag) FileSettings(fileNo byte) (DESFireFileSettings, error)我應(yīng)該如何進行？
1 回答
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TA貢獻1934條經(jīng)驗 獲得超2個贊
您需要考慮如何更新聯(lián)合中的字段。顯然，你不能讓用戶在沒有驗證的情況下這樣做。他們可能會進行不一致的更新。考慮做這樣的事情：
package mifare
const (
MDFTStandarDataFile = 0x00
MDFTBackupDataFile = 0x01
MDFTValueFileWithBackup = 0x02
MDFTLinearRecordFileWithBackup = 0x03
MDFTCyclicRecordFileWithBackup = 0x04
)
type StandardFile struct {
FileSize uint32
}
type ValueFile struct {
LowerLimit int32
UpperLimit int32
LimitedCreditValue int32
LimitedCreditEnabled uint8
}
type LinearRecordFile struct {
Record_size uint32
MaxNumberOfRecords uint32
CurrentNumberOfRecords uint32
}
type DESFireFileSettings struct {
FileType uint8
CommunicationSettings uint8
AccessRights uint16
settings struct {
StandardFile
ValueFile
LinearRecordFile
}
}
func (fs *DESFireFileSettings) StandardFile() (StandardFile, error) {
// if not valid for FileType, return error
return fs.settings.StandardFile, nil
}
func (fs *DESFireFileSettings) SetStandardFile(standardFile StandardFile) error {
// if not valid for FileType, return error
fs.settings.StandardFile = standardFile
return nil
}
func (fs *DESFireFileSettings) ValueFile() (ValueFile, error) {
// if not valid for FileType, return error
return fs.settings.ValueFile, nil
}
func (fs *DESFireFileSettings) SetValueFile(valueFile ValueFile) error {
// if not valid for FileType, return error
fs.settings.ValueFile = valueFile
return nil
}
func (fs *DESFireFileSettings) LinearRecordFile() (LinearRecordFile, error) {
// if not valid for FileType, return error
return fs.settings.LinearRecordFile, nil
}
func (fs *DESFireFileSettings) SetLinearRecordFile(linearRecordFile LinearRecordFile) error {
// if not valid for FileType, return error
fs.settings.LinearRecordFile = linearRecordFile
return nil
}
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